Docs: Add info about custom worlds (#5510)

* Cleaning up (#4)

Cleanup

* Added new paragraph for new games

* Update worlds/generic/docs/setup_en.md

Proofier-comitting

Co-authored-by: Exempt-Medic <60412657+Exempt-Medic@users.noreply.github.com>

* Added a mention in the header of the games page to refer to this guide if needed.

* Small tweaks

* Added mention regarding alternate version of worlds

* Update WebHostLib/templates/supportedGames.html

Co-authored-by: Exempt-Medic <60412657+Exempt-Medic@users.noreply.github.com>

* Update worlds/generic/docs/setup_en.md

Co-authored-by: Exempt-Medic <60412657+Exempt-Medic@users.noreply.github.com>

* Edits for comments

* Slight alternate versions rewording

* Edit subheadings

* Adjust link text

* Replace alternate versions section and reword first

---------

Co-authored-by: Danaël V <104455676+ReverM@users.noreply.github.com>
Co-authored-by: Rever <danael.villeneuve@gmail.com>
Co-authored-by: Exempt-Medic <60412657+Exempt-Medic@users.noreply.github.com>

WebHostLib/templates/supportedGames.html

@@ -31,6 +31,9 @@
     {% include 'header/oceanHeader.html' %}
     <div id="games" class="markdown">
         <h1>Currently Supported Games</h1>
+        <p>Below are the games that are currently included with the Archipelago software. To play a game that is not on
+        this page, please refer to the <a href="/tutorial/Archipelago/setup/en#playing-with-custom-worlds">playing with
+        custom worlds</a> section of the setup guide.</p>
         <div class="js-only">
             <label for="game-search">Search for your game below!</label><br />
             <div class="page-controls">