gptel, gptel-curl: Address checkdoc warnings

* gptel.el (gptel--url-parse-response, gptel-max-tokens,
gptel-use-header-line): Address checkdoc warnings.

* gptel-curl.el (gptel-curl--parse-response, gptel-abort):
Address checkdoc warnings.

* gptel-gemini (gptel-make-gemini): Address checkdoc warnings.

gptel-curl.el

@@ -139,7 +139,7 @@ the response is inserted into the current buffer after point."
         (set-process-sentinel process #'gptel-curl--sentinel)))))
 
 (defun gptel-abort (buf)
-  "Stop any active gptel process associated with the current buffer."
+  "Stop any active gptel process associated with buffer BUF."
   (interactive (list (current-buffer)))
   (unless gptel-use-curl
     (user-error "Cannot stop a `url-retrieve' request!"))
@@ -295,9 +295,9 @@ See `gptel--url-get-response' for details."
       (when-let ((http-msg (plist-get proc-info :status))
                  (http-status (plist-get proc-info :http-status)))
         ;; Find data chunk(s) and run callback
-        (when-let ((_ (equal http-status "200"))
+        (when-let (((equal http-status "200"))
                    (response (funcall (plist-get proc-info :parser) nil proc-info))
-                   (_ (not (equal response ""))))
+                   ((not (equal response ""))))
           (funcall (or (plist-get proc-info :callback)
                        #'gptel-curl--stream-insert-response)
                    response proc-info))))))
@@ -337,8 +337,7 @@ PROCESS and _STATUS are process parameters."
 (defun gptel-curl--parse-response (proc-info)
   "Parse the buffer BUF with curl's response.
 
-TOKEN is used to disambiguate multiple requests in a single
+PROC-INFO is a plist with contextual information."
-buffer."
   (let ((token (plist-get proc-info :token))
         (parser (plist-get proc-info :parser)))
     (goto-char (point-max))

gptel-gemini.el

@@ -115,7 +115,7 @@ HOST (optional) is the API host, defaults to
 MODELS is a list of available model names.  Currently only
 \"gemini-pro\" is available.
 
-STREAM is a boolean to toggle streaming responses, defaults to
+STREAM is a boolean to enable streaming responses, defaults to
 false.
 
 PROTOCOL (optional) specifies the protocol, \"https\" by default.

gptel.el

@@ -29,7 +29,8 @@
 
 ;; gptel is a simple Large Language Model chat client, with support for multiple models/backends.
 ;;
-;; gptel supports ChatGPT, Azure, and local models using Ollama and GPT4All.
+;; gptel supports ChatGPT, Azure, Gemini and local models using Ollama and
+;; GPT4All.
 ;;
 ;;  Features:
 ;;  - It’s async and fast, streams responses.
@@ -44,8 +45,8 @@
 ;; Requirements for ChatGPT, Azure or Gemini:
 ;;
 ;; - You need an appropriate API key.  Set the variable `gptel-api-key' to the
-;;   key or to a function of no arguments that returns the key. (It tries to use
+;;   key or to a function of no arguments that returns the key.  (It tries to
-;;   `auth-source' by default)
+;;   use `auth-source' by default)
 ;;
 ;; - For Azure: define a gptel-backend with `gptel-make-azure', which see.
 ;; - For Gemini: define a gptel-backend with `gptel-make-gemini', which see.
@@ -197,8 +198,8 @@ such as filling paragraphs, adding annotations or recording
 information in the response like links.
 
 Each function in this hook receives two arguments, the response
-string to transform and the ChatGPT interaction buffer. It should
+string to transform and the ChatGPT interaction buffer.  It
-return the transformed string."
+should return the transformed string."
   :group 'gptel
   :type 'hook)
 
@@ -276,7 +277,8 @@ is only inserted in dedicated gptel buffers before the AI's response."
   :type '(alist :key-type symbol :value-type string))
 
 (defcustom gptel-use-header-line t
-  "Whether gptel-mode should use the header-line for status information.
+  "Whether `gptel-mode' should use header-line for status
+information.
 
 When set to nil, use the mode line for (minimal) status
 information and the echo area for messages."
@@ -1008,7 +1010,7 @@ PROC-INFO is a plist with process information and other context.
 See `gptel-curl--get-response' for its contents.")
 
 (defun gptel--url-parse-response (backend response-buffer)
-  "Parse response in RESPONSE-BUFFER."
+  "Parse response from BACKEND in RESPONSE-BUFFER."
   (when (buffer-live-p response-buffer)
     (when gptel--debug
       (with-current-buffer response-buffer