Base: Add some "See also" links to the man pages

We can do this now that we have link support in LibMarkdown and LibHTML ^)

Base/usr/share/man/man1/mkdir.md

@@ -17,3 +17,7 @@ Create a new empty directory at the given *path*.
 ```sh
 $ mkdir /tmp/foo
 ```
+
+## See also
+
+* [`mkdir`(2)](../man2/mkdir.md)

Base/usr/share/man/man2/create_shared_buffer.md

@@ -21,3 +21,7 @@ If a region is successfully created, `create_shared_buffer()` stores a pointer t
 
 * `EINVAL`: `size` is zero or negative.
 * `EFAULT`: `buffer` is not a valid address.
+
+## See also
+
+* [`share_buffer_with`(2)](share_buffer_with.md)

Base/usr/share/man/man2/mkdir.md

@@ -18,3 +18,7 @@ Create a new empty directory at the given *path* using the given *mode*.
 
 If the directory was created successfully, `mkdir()` returns 0. Otherwise,
 it returns -1 and sets `errno` to describe the error.
+
+## See also
+
+* [`mkdir`(1)](../man1/mkdir.md)

Base/usr/share/man/man2/share_buffer_with.md

@@ -22,3 +22,7 @@ On success, returns 0. Otherwise, returns -1 and `errno` is set.
 * `EINVAL`: `peer_pid` is invalid, or `shared_buffer_id` is not a valid ID.
 * `EPERM`: The calling process does not have access to the buffer with `shared_buffer_id`.
 * `ESRCH`: No process with PID `peer_pid` is found.
+
+## See also
+
+* [`create_shared_buffer`(2)](create_shared_buffer.md)