docs: add client spec for vesting (#10336)

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## Description

Closes: #10293 

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x/auth/spec/07_client.md

@@ -0,0 +1,45 @@
+<!--
+order: 7
+-->
+
+# Client
+
+## CLI
+
+A user can query and interact with the `vesting` module using the CLI.
+
+### Transactions
+
+The `tx` commands allow users to interact with the `vesting` module.
+
+```bash
+simd tx vesting --help
+```
+
+#### create-periodic-vesting-account
+
+The `create-periodic-vesting-account` command creates a new vesting account funded with an allocation of tokens, where a sequence of coins and period length in seconds. Periods are sequential, in that the duration of of a period only starts at the end of the previous period. The duration of the first period starts upon account creation.
+
+```bash
+simd tx vesting create-periodic-vesting-account [to_address] [periods_json_file] [flags]
+```
+
+Example:
+
+```bash
+simd tx vesting create-periodic-vesting-account cosmos1.. periods.json
+```
+
+#### create-vesting-account
+
+The `create-vesting-account` command creates a new vesting account funded with an allocation of tokens. The account can either be a delayed or continuous vesting account, which is determined by the '--delayed' flag. All vesting accouts created will have their start time set by the committed block's time. The end_time must be provided as a UNIX epoch timestamp.
+
+```bash
+simd tx vesting create-vesting-account [to_address] [amount] [end_time] [flags]
+```
+
+Example:
+
+```bash
+simd tx vesting create-vesting-account cosmos1.. 100stake 2592000
+```

x/auth/spec/README.md

@@ -36,4 +36,6 @@ This module is used in the Cosmos Hub.
    - [Genesis Initialization](05_vesting.md#genesis-initialization)
    - [Examples](05_vesting.md#examples)
    - [Glossary](05_vesting.md#glossary)
-6. **[Parameters](07_params.md)**
+6. **[Parameters](06_params.md)**
+7. **[Client](07_client.md)**
+   - [CLI](07_client.md#cli)