readme: Use devel as default branch

Author: jorisv

development/release.md

@@ -6,7 +6,6 @@ To create a release with Pixi run the following commands on the **devel** branch
 EIGENPY_VERSION=X.Y.Z pixi run release_new_version
 git push origin
 git push origin vX.Y.Z
-git push origin devel:master
 ```
 
 Where `X.Y.Z` is the new version.