gptel-gh: Update README and docstrings

Author: marcus-lundgren

README.org

@@ -1089,8 +1089,18 @@ However private endpoints can be configure like so -
     :host "api.business.githubcopilot.com")
 #+end_src
 
-You will be informed to login into =GitHub= as required.
-You can pick this backend from the menu when using gptel (see [[#usage][Usage]]).
+You will be informed to login into =GitHub= as required. You can pick this backend from the menu when using gptel (see [[#usage][Usage]]).
+
+The GitHub OAuth token is stored by default in a cleartext file based on the path stored in =gptel-gh-github-token-file=. It is possible to customize the variables =gptel-gh-github-token-load-function= and =gptel-gh-github-token-save-function= to change this behavior. If the token is e.g. stored in a password manager, then the following example can be used to so that the token is read as a password:
+
+#+begin_src emacs-lisp
+(setq
+ ;; Prompt user to provide the token as a password
+ gptel-gh-github-token-load-function (lambda () (read-passwd "Copilot token: "))
+
+ ;; Display a message when a new token has been stored, so that it can be copied from the message history
+ gptel-gh-github-token-save-function (lambda (token) (message "Token saved: %s" token)))
+#+end_src
 
 ***** (Optional) Set as the default gptel backend
 

gptel-gh.el

@@ -152,12 +152,12 @@
   :group 'gptel)
 
 (defcustom gptel-gh-github-token-load-function 'gptel--gh-restore-from-file
-  "Function to load the current github token."
+  "Function to load the current github token. Default behavior is file-based based on `gptel-gh-github-token-file'."
   :type 'function
   :group 'gptel)
 
 (defcustom gptel-gh-github-token-save-function 'gptel--gh-save-to-file
-  "Function to save the new github token."
+  "Function to save the new github token. Default behavior is file-based based on `gptel-gh-github-token-file'."
   :type 'function
   :group 'gptel)