docs(x/feegrant): use `coins` instead of `tokens` (#12444)

## Description

Closes: #12422 



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

api/cosmos/feegrant/v1beta1/feegrant.pulsar.go

@@ -2597,15 +2597,15 @@ const (
 	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
 )
 
-// BasicAllowance implements Allowance with a one-time grant of tokens
+// BasicAllowance implements Allowance with a one-time grant of coins
 // that optionally expires. The grantee can use up to SpendLimit to cover fees.
 type BasicAllowance struct {
 	state         protoimpl.MessageState
 	sizeCache     protoimpl.SizeCache
 	unknownFields protoimpl.UnknownFields
 
-	// spend_limit specifies the maximum amount of tokens that can be spent
-	// by this allowance and will be updated as tokens are spent. If it is
+	// spend_limit specifies the maximum amount of coins that can be spent
+	// by this allowance and will be updated as coins are spent. If it is
 	// empty, there is no spend limit and any amount of coins can be spent.
 	SpendLimit []*v1beta1.Coin `protobuf:"bytes,1,rep,name=spend_limit,json=spendLimit,proto3" json:"spend_limit,omitempty"`
 	// expiration specifies an optional time when this allowance expires

proto/cosmos/feegrant/v1beta1/feegrant.proto

@@ -11,13 +11,13 @@ import "google/protobuf/duration.proto";
 
 option go_package = "github.com/cosmos/cosmos-sdk/x/feegrant";
 
-// BasicAllowance implements Allowance with a one-time grant of tokens
+// BasicAllowance implements Allowance with a one-time grant of coins
 // that optionally expires. The grantee can use up to SpendLimit to cover fees.
 message BasicAllowance {
   option (cosmos_proto.implements_interface) = "FeeAllowanceI";
 
-  // spend_limit specifies the maximum amount of tokens that can be spent
-  // by this allowance and will be updated as tokens are spent. If it is
+  // spend_limit specifies the maximum amount of coins that can be spent
+  // by this allowance and will be updated as coins are spent. If it is
   // empty, there is no spend limit and any amount of coins can be spent.
   repeated cosmos.base.v1beta1.Coin spend_limit = 1
       [(gogoproto.nullable) = false, (gogoproto.castrepeated) = "github.com/cosmos/cosmos-sdk/types.Coins"];

x/feegrant/doc.go

@@ -5,7 +5,7 @@ fees from one account (key) to another account (key).
 Effectively, this allows for a user to pay fees using the balance of an account
 different from their own. Example use cases would be allowing a key on a device to
 pay for fees using a master wallet, or a third party service allowing users to
-pay for transactions without ever really holding their own tokens. This package
+pay for transactions without ever really holding their own coins. This package
 provides ways for specifying fee allowances such that authorizing fee payment to
 another account can be done with clear and safe restrictions.
 

x/feegrant/feegrant.pb.go

@@ -32,11 +32,11 @@ var _ = time.Kitchen
 // proto package needs to be updated.
 const _ = proto.GoGoProtoPackageIsVersion3 // please upgrade the proto package
 
-// BasicAllowance implements Allowance with a one-time grant of tokens
+// BasicAllowance implements Allowance with a one-time grant of coins
 // that optionally expires. The grantee can use up to SpendLimit to cover fees.
 type BasicAllowance struct {
-	// spend_limit specifies the maximum amount of tokens that can be spent
-	// by this allowance and will be updated as tokens are spent. If it is
+	// spend_limit specifies the maximum amount of coins that can be spent
+	// by this allowance and will be updated as coins are spent. If it is
 	// empty, there is no spend limit and any amount of coins can be spent.
 	SpendLimit github_com_cosmos_cosmos_sdk_types.Coins `protobuf:"bytes,1,rep,name=spend_limit,json=spendLimit,proto3,castrepeated=github.com/cosmos/cosmos-sdk/types.Coins" json:"spend_limit"`
 	// expiration specifies an optional time when this allowance expires

x/feegrant/spec/01_concepts.md

@@ -28,11 +28,11 @@ There are two types of fee allowances present at the moment:
 
 +++ https://github.com/cosmos/cosmos-sdk/blob/v0.46.0-rc1/proto/cosmos/feegrant/v1beta1/feegrant.proto#L13-L26
 
-* `spend_limit` is the limit of coins that are allowed to be used from the `granter` account. If it is empty, it assumes there's no spend limit, `grantee` can use any number of available tokens from `granter` account address before the expiration.
+* `spend_limit` is the limit of coins that are allowed to be used from the `granter` account. If it is empty, it assumes there's no spend limit, `grantee` can use any number of available coins from `granter` account address before the expiration.
 
 * `expiration` specifies an optional time when this allowance expires. If the value is left empty, there is no expiry for the grant.
 
-* When a grant is created with empty values for `spend_limit` and `expiration`, it is still a valid grant. It won't restrict the `grantee` to use any number of tokens from `granter` and it won't have any expiration. The only way to restrict the `grantee` is by revoking the grant.
+* When a grant is created with empty values for `spend_limit` and `expiration`, it is still a valid grant. It won't restrict the `grantee` to use any number of coins from `granter` and it won't have any expiration. The only way to restrict the `grantee` is by revoking the grant.
 
 ## PeriodicAllowance