chore: add reference to word list generation script repo (#5045)

Author: mnemotic

dictionaries/gdscript/src/README.md

@@ -3,5 +3,7 @@
 All source files used to generate the dictionary should be stored in this directory.
 
 Main word list `gdscript-words/gdscript.txt` is generated from Godot
-documentation and should not be modified manually. Instead, any additional words
-should be added to `gdscript.txt`.
+documentation using a script from
+[mnemotic/gdscript-words](https://github.com/mnemotic/gdscript-words) (see
+`gdscript-words/README.md`) and should not be modified manually. Instead, any
+additional words should be added to `gdscript.txt`.