Brush up validator start docs (#7333)

* Brush up validator start docs

* Gut Choosing a Testnet to be less confusing

book/src/running-validator/validator-software.md

@@ -8,6 +8,10 @@ machine by running:
 curl -sSf https://raw.githubusercontent.com/solana-labs/solana/v0.21.0/install/solana-install-init.sh | sh -s - 0.21.0
 ```
 
+If you are connecting to a different testnet, you can replace `0.21.0` with the
+release tag matching the software version of your desired testnet, or replace it
+with the named channel `stable`, `beta`, or `edge`.
+
 The following output indicates a successful update:
 
 ```text

book/src/running-validator/validator-start.md

@@ -1,16 +1,24 @@
 # Starting a Validator
 
+## Configure Solana CLI
+
+The solana cli includes `get` and `set` configuration commands to automatically
+set the `--url` argument for cli commands. For example:
+
+```bash
+solana set --url http://testnet.solana.com:8899
+```
+
+\(You can always override the set configuration by explicitly passing the
+`--url` argument with a command, eg: `solana --url http://beta.testnet.solana.com:8899 balance`\)
+
 ## Confirm The Testnet Is Reachable
 
 Before attaching a validator node, sanity check that the cluster is accessible
-to your machine by running some simple commands. If any of the commands fail,
-please retry 5-10 minutes later to confirm the testnet is not just restarting
-itself before debugging further.
-
-Fetch the current transaction count over JSON RPC:
+to your machine by fetching the transaction count:
 
 ```bash
-curl -X POST -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1, "method":"getTransactionCount"}' http://testnet.solana.com:8899
+solana get-transaction-count
 ```
 
 Inspect the network explorer at
@@ -90,13 +98,13 @@ solana-keygen grind --starts-with e1v1s
 
 Depending on the string requested, it may take days to find a match...
 
-## Wallet Configuration
+## More Solana CLI Configuration
 
-Set solana configuration to use your validator keypair and the stable
-testnet for all following commands:
+Now that you have a keypair, set the solana configuration to use your validator
+keypair for all following commands:
 
 ```bash
-solana set --url http://testnet.solana.com:8899 --keypair ~/validator-keypair.json
+solana set --keypair ~/validator-keypair.json
 ```
 
 You should see the following output:

book/src/running-validator/validator-testnet.md

@@ -17,70 +17,17 @@ tracks the most stable tagged release.
 
 ### Get Testnet Version
 
-You can submit a JSON-RPC request to see the specific version of the cluster.
+You can submit a JSON-RPC request to see the specific software version of the
+cluster. Use this to specify [the software version to install](validator-software.md).
 
 ```bash
-curl -X POST -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1, "method":"getVersion"}' edge.testnet.solana.com:8899
-{"jsonrpc":"2.0","result":{"solana-core":"0.21.0"},"id":1}
+curl -X POST -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1, "method":"getVersion"}' testnet.solana.com:8899
 ```
+Example result:
+`{"jsonrpc":"2.0","result":{"solana-core":"0.21.0"},"id":1}`
 
 ## Using a Different Testnet
 
 This guide is written in the context of testnet.solana.com, our most stable
-cluster. To participate in another testnet, you will need to modify some of the
-commands in the following pages.
-
-### Downloading Software
-
-If you are bootstrapping with `solana-install`, you can specify the release tag
-or named channel to install to match your desired testnet.
-
-```bash
-curl -sSf https://raw.githubusercontent.com/solana-labs/solana/v0.21.0/install/solana-install-init.sh | sh -s - 0.21.0
-```
-
-```bash
-curl -sSf https://raw.githubusercontent.com/solana-labs/solana/v0.21.0/install/solana-install-init.sh | sh -s - beta
-```
-
-Similarly, you can add this argument to the `solana-install` command if you've built the program from source:
-
-```bash
-solana-install init 0.21.0
-```
-
-If you are downloading pre-compiled binaries or building from source, simply
-choose the release matching your desired testnet.
-
-### Validator Commands
-
-The Solana CLI tool points at testnet.solana.com by default. Include a `--url`
-argument to point at a different testnet. For instance:
-
-```bash
-solana --url http://beta.testnet.solana.com:8899 balance
-```
-
-The solana cli includes `get` and `set` configuration commands to automatically
-set the `--url` argument for future cli commands. For example:
-
-```bash
-solana set --url http://beta.testnet.solana.com:8899
-```
-
-\(You can always override the set configuration by explicitly passing the
-`--url` argument with a command.\)
-
-Solana-gossip and solana-validator commands already require an explicit
-`--entrypoint` argument. Simply replace testnet.solana.com in the examples with
-an alternate url to interact with a different testnet. For example:
-
-```bash
-solana-validator --identity-keypair ~/validator-keypair.json --voting-keypair ~/validator-vote-keypair.json --ledger ~/validator-config --rpc-port 8899 beta.testnet.solana.com
-```
-
-You can also submit JSON-RPC requests to a different testnet, like:
-
-```bash
-curl -X POST -H 'Content-Type: application/json' -d '{"jsonrpc":"2.0","id":1, "method":"getTransactionCount"}' http://beta.testnet.solana.com:8899
-```
+cluster. To participate in another testnet, modify the commands in the following
+pages, replacing `testnet.solana.com` with your desired testnet.