docs: improve SSH age doc in README

Signed-off-by: Nate Scherer <376408+natescherer@users.noreply.github.com>

Author: natescherer

README.rst

@@ -253,13 +253,13 @@ Encrypting with SSH keys via age is also supported by SOPS. You can use SSH publ
 
 When decrypting a file, SOPS will attempt to source the SSH private key as follows:
 
-1. From the path specified in environment variable **SOPS_AGE_SSH_PRIVATE_KEY_FILE**
-2. From the output of the command specified in environment variable **SOPS_AGE_SSH_PRIVATE_KEY_CMD**
+- From the path specified in environment variable **SOPS_AGE_SSH_PRIVATE_KEY_FILE**.
+- From the output of the command specified in environment variable **SOPS_AGE_SSH_PRIVATE_KEY_CMD**.
 
-   .. note:: The output of this command must provide a key that is not password protected
+   .. note:: The output of this command must provide a key that is not password protected.
 
-3. From ``~/.ssh/id_ed25519``
-4. From ``~/.ssh/id_rsa``.
+- From ``~/.ssh/id_ed25519``.
+- From ``~/.ssh/id_rsa``.
 
 Note that only ``ssh-rsa`` and ``ssh-ed25519`` are supported.