Base: Move GUI application man pages into their own subsection

We do not want to move POSIX utilities into subsections since they have
standard names, but we can do whatever we want with Applications :^).
This is particularly advantageous as many applications contain several
images, which declutters the man1 directory.

Base/usr/share/man/man1/Applications/Help.md

@@ -0,0 +1,50 @@
+## Name
+
+![Icon](/res/icons/16x16/app-help.png) Help - digital manual
+
+[Open](file:///bin/Help)
+
+## Synopsis
+
+```**sh
+$ Help
+$ Help [section] page
+$ Help search_query
+$ Help file
+```
+
+## Description
+
+`Help` is Serenity's digital manual, the GUI counterpart to `man`.
+It lets you search for and read manual pages (or "man pages").
+
+## Examples
+
+To open Help:
+```sh
+$ Help
+```
+
+To open documentation for the `echo` command:
+```sh
+$ Help echo
+```
+
+To open the documentation for the `mkdir` command:
+```sh
+$ Help 1 mkdir
+```
+Conversely, to open the documentation about the `mkdir()` syscall:
+```sh
+$ Help 2 mkdir
+```
+
+## Files
+
+`Help` looks for man pages under `/usr/share/man`. For example,
+this man page should be located at `/usr/share/man/man1/Help.md`.
+
+## See Also
+
+* [`man`(1)](help://man/1/man) To read these same man pages from the terminal
+* [`man`(7)](help://man/7/man) For an overview on how manpages are organized