Merge branch 'readme' into 'pregmod-master'

Add repo that contains the changes to SC2.

See merge request !6796

README.md

@@ -76,3 +76,8 @@ How to mod (basic doc):
 	4. Make you changes as you like, commit, and push result into your forked repository (with git client).
 	5. (optional, but recommended) Run sanityCheck before final push to catch any errors you missed. (You can ignore errors unrelated to files you changed.)
 	6. Make merge request through gitgud interface.
+
+## Related repositories
+
+FC uses a modified version of SugarCube 2. The sources can either be obtained preferably via [this repo](https://gitgud.io/Arkerthan/sugarcube-2) or by applying the patch to the official SC2 files.
+When modifying SC2 make sure to open an MR here and at the SC2 repo, so they stay in sync. 

devNotes/sugarcube stuff/building SugarCube.md

@@ -27,7 +27,9 @@ commit to commit and it differs between branches! Make sure to install correct d
 
 ## Applying the FC patch
 
-The FreeCities game relies on a few changes to the vanilla SugarCube code. In this repository they are kept as patch files. The SugarCube code changes from version to version that requires modification to the patch file, and therefore there are several of them, named after the highest SugarCube version they applies to. There are at least two different ways to manage the patches/changes, with the first one suitable for occasional users, while the second one works best if you maintain the SugarCube patch for the FC project or just want to keep building for more than a single SugarCube version.
+The FreeCities game relies on a few changes to the vanilla SugarCube code. The modified SC2 can be found [here](https://gitgud.io/Arkerthan/sugarcube-2).
+
+If unavailable, it is possible to patch the official SC2 sources using the patch file. The SugarCube code changes from version to version that requires modification to the patch file, and therefore there are several of them, named after the highest SugarCube version they applies to. There are at least two different ways to manage the patches/changes, with the first one suitable for occasional users, while the second one works best if you maintain the SugarCube patch for the FC project or just want to keep building for more than a single SugarCube version.
 
 ### Single time patching