Initial proposal for rule 9 script (#68)

* Initial proposal for rule 9 script

I'm not super confidant that it covers our needs, or even reads well (lol I say this and I'm a native english speaker)

* Add Rule 9 to the issue template

* Reword rule 9 to not mention internals.

As per @bell07's earlier request in #68.

Rewording done by @dacmot.

Co-authored-by: Olivier Dragon <odragon@protonmail.com>

Co-authored-by: Olivier Dragon <odragon@protonmail.com>

.github/ISSUE_TEMPLATE/mod_request.md

@@ -32,5 +32,7 @@ https://www.example.com
   - 
 8. Does this mod use the software "git" for version control? (note: we are asking about git. Github, Gitlab, notabug and hundreds of other git _providers_ exist but are not specificly needed, although these do qualify).
   - 
+9. Upon testing this mod, what errors, odd behavior, or other incompatibilities were noticed?
+  - 
 
 ## Other comments

README.md

@@ -62,3 +62,7 @@ The mods should not feel like cheats. The tools should be worn, walking through
 ### 8 Mod under version control
 
 This game is not a new home for mods. Each mod remains within and have their own upstream. Access by version control is required for scripted updates to the game. If bugs are found in mods in this game, please report them to the upstream sources.
+
+### 9 Mod must not be incompatible with other mods
+
+Mods should not require compatibility code to be added to the Why Not? game, and thus requiring extra maintenance work on our part. If we find incompatibilities (ex. recipes conflicts, redundant items, keypress overlap) we expect any required changes to happen upstream before the mod is added to whynot. Some exceptions may be considered on a case-by-case basis.