Add the org-clock-waybar-output-task function

It outputs the generated JSON string to the standard output so it can
be used directly from the command line, e.g. using `emacsclient`.

README.md

@@ -6,13 +6,15 @@ Put `org-clock-waybar.el` somewhere in your `load-path`, and `(require 'org-cloc
 
 MELPA version may come soon.
 
-You can set the file to be written by customizing `org-clock-waybar-filename`; it defaults to `$XDG_CACHE_HOME/waybar-current-task.json` (`$XDG_CACHE_HOME` defaults to `$HOME/.cache` on XDG compatible systems, like Linux.)
+You can set the file to be written by customizing `org-clock-waybar-filename`; it defaults to
+`$XDG_CACHE_HOME/waybar-current-task.json` (`$XDG_CACHE_HOME` defaults to `$HOME/.cache` on XDG
+compatible systems, like Linux.)
 
 ## Waybar configuration
 
 To add the current task to Waybar, add this snippet to your config:
 
-```
+```json
 "custom/org": {
   "format": " {}",
   "return-type": "json",
@@ -21,7 +23,23 @@ To add the current task to Waybar, add this snippet to your config:
 }
 ```
 
-Then, add `custom/org` to `modules-left`/`modules-center`/`module-right` if your bar’s configuration.  You can find a minimal working configuration in the [`examples`](./examples) directory.
+If you use Emacs as a daemon (e.g. starting it as `emacs --daemon` or calling `(server-start)`),
+you can change the `exec` command to invoke `emacsclient` directly.  In this case, no output file
+will be written.:
+
+```json
+"custom/org": {
+  "format": " {}",
+  "return-type": "json",
+  "restart-interval": 5,
+  "exec": "emacsclient --eval '(org-clock-waybar-ouptut-task)'"
+}
+
+```
+
+Then, add `custom/org` to `modules-left`/`modules-center`/`module-right` if your bar’s
+configuration.  You can find a minimal working configuration in the [`examples`](./examples)
+directory.
 
 ## Customization
 

org-clock-waybar.el

@@ -95,6 +95,14 @@ value of `org-clock-waybar-not-clocked-in-text'."
     (insert (org-clock-waybar--get-clocked-task-json))
     (write-file org-clock-waybar-filename)))
 
+(defun org-clock-waybar-ouptut-task ()
+  "Output the current task in JSON format Waybar can understand.
+
+This function is ought to be used via Emacsclient:
+
+emacsclient --eval '(org-clock-waybar-output-task)'"
+  (print (org-clock-waybar--get-clocked-task-json)))
+
 (defun org-clock-waybar-setup ()
   "Setup org-clock-waybar.