Clean up paper/file system wallet docs (#9340)

* Add filesystem wallet page

* Move validator paper wallet instructions to validator page

* Remove paper wallet staking section

* Add steps for multiple fs and paper wallets

* Add keypair convention page and better multi-wallet example

docs/src/file-system-wallet/README.md

@@ -0,0 +1,64 @@
+# File System Wallet
+
+This document describes how to create and use a file system wallet with the
+Solana CLI tools.  A file system wallet exists as an unencrypted keypair file
+on your computer system's filesystem.
+
+{% hint style="info" %}
+File system wallets are the **least secure** method of storing SOL tokens.
+Storing large amounts of tokens in a file system wallet is **not recommended**.
+{% endhint %}
+
+## Before you Begin
+Make sure you have
+[installed the Solana Command Line Tools](../cli/install-solana-cli-tools.md)
+
+## Generate a File System Wallet Keypair
+
+Use Solana's command-line tool `solana-keygen` to generate keypair files. For
+example, run the following from a command-line shell:
+
+```bash
+mkdir ~/my-solana-wallet
+solana-keygen new --outfile ~/my-solana-wallet/my-keypair.json
+```
+
+This file contains your **unencrypted** keypair. In fact, even if you specify
+a password, that password applies to the recovery seed phrase, not the file. Do
+not share this file with others. Anyone with access to this file will have access
+to all tokens sent to its public key. Instead, you should share only its public
+key. To display its public key, run:
+
+```bash
+solana-keygen pubkey ~/my-solana-wallet/my-keypair.json
+```
+
+It will output a string of characters, such as:
+
+```text
+ErRr1caKzK8L8nn4xmEWtimYRiTCAZXjBtVphuZ5vMKy
+```
+
+This is the public key corresponding to the keypair in
+`~/my-solana-wallet/my-keypair.json`.  The public key of the keypair file is
+your *wallet address*.
+
+## Verify your Address against your Keypair file
+
+To verify you hold the private key for a given address, use
+`solana-keygen verify`:
+
+```bash
+solana-keygen verify <PUBKEY> ~/my-solana-wallet/my-keypair.json
+```
+
+where `<PUBKEY>` is replaced with your wallet address.
+The command will output "Success" if the given address matches the
+the one in your keypair file, and "Failed" otherwise.
+
+## Creating Multiple File System Wallet Addresses
+You can create as many wallet addresses as you like.  Simply re-run the
+steps in [Generate a File System Wallet](#generate-a-file-system-wallet-keypair)
+and make sure to use a new filename or path with the `--outfile` argument.
+Multiple wallet addresses can be useful if you want to transfer tokens between
+your own accounts for different purposes.