Many issues in the wiki were unnecessarily links:
```
... patch posted in [\#1346](ghc#1346).
```
This rewrites these as `#1346` using
```bash
sed -i -r -e 's/\[\\#([0-9]+)\]\([^)]+\/\1\)/#\1/g' $(find -iname '*.md')
```
And manually eyeballing the result.

proposal/custom-type-errors.md

@@ -5,7 +5,7 @@ This page outlines the design for a GHC feature to provide support for user-spec
 The main idea was [presented by Lennart Augustsson at the 2015 Haskell Symposium in Vancouver BC](https://youtu.be/ZlZbSiYrqcQ). 
 
 
-The relevant ticket is [\#9637](https://gitlab.haskell.org/ghc/ghc/issues/9637).
+The relevant ticket is #9637.
 
 ## Status