Docs: Add cmd_psuh with repo and UNUSED removal

This commit improves the `cmd_psuh` documentation example by:

Correcting the function signature to include struct repository *repo.
Makes the signature accurate and consistent with typical Git built-in
commands.

Removing the `UNUSED` macros from the `cmd_psuh` function arguments
(argc, argv, prefix, repo). This is done because the example now
uses these arguments.

Showing how to access the repository's Git directory (repo->gitdir)
within the cmd_psuh function. This provides a practical example of
how to use the repo argument and repository-related information.

Keeps your existing printf() calls in place.
This lets the users see the arguments which is given to the function.

This enhanced example provides a more complete illustration of
Adding a Git built-in command and use the repository argument.

Signed-off-by: K Jayatheerth <[email protected]>

Author: jayatheerthkulkarni

Documentation/MyFirstContribution.adoc

@@ -158,7 +158,7 @@ declaration for `cmd_pull`, and add a new line for `psuh` immediately before it,
 in order to keep the declarations alphabetically sorted:
 
 ----
-int cmd_psuh(int argc, const char **argv, const char *prefix);
+int cmd_psuh(int argc, const char **argv, const char *prefix, struct repository *repo);
 ----
 
 Be sure to `#include "builtin.h"` in your `psuh.c`. You'll also need to
@@ -174,7 +174,8 @@ Throughout the tutorial, we will mark strings for translation as necessary; you
 should also do so when writing your user-facing commands in the future.
 
 ----
-int cmd_psuh(int argc, const char **argv, const char *prefix)
+int cmd_psuh(int argc UNUSED, const char **argv UNUSED, 
+			const char *prefix UNUSED, struct repository *repo UNUSED)
 {
 	printf(_("Pony saying hello goes here.\n"));
 	return 0;
@@ -287,10 +288,14 @@ on the reference implementation linked at the top of this document.
 It's probably useful to do at least something besides printing out a string.
 Let's start by having a look at everything we get.
 
-Modify your `cmd_psuh` implementation to dump the args you're passed, keeping
+Modify your `cmd_psuh` implementation to dump the args you're passed
+and removing the UNUSED macro from them, keeping
 existing `printf()` calls in place:
 
 ----
+int cmd_psuh(int argc, const char **argv, 
+			const char *prefix, struct repository *repo)
+{
 	int i;
 
 	...
@@ -305,6 +310,14 @@ existing `printf()` calls in place:
 	printf(_("Your current working directory:\n<top-level>%s%s\n"),
 	       prefix ? "/" : "", prefix ? prefix : "");
 
+	if (repo && repo->gitdir) {
+        printf(_("Git directory: %s\n"), repo->gitdir);
+    } else {
+        printf(_("No Git directory found.\n"));
+    }
+
+	...
+}
 ----
 
 Build and try it. As you may expect, there's pretty much just whatever we give