Add note on filtering

README.md

@@ -15,7 +15,7 @@ The repository `ecg-prog-filtered` only includes files solely written by me.
 It is filtered with the `./filter.sh` script.
 Please **don’t** rely on the history of this repository,
 as rewriting is part of how it can exist.
-See [Licence](#Licence) for more information on the licencing.
+See [Licences](#Licences) for more information on the licencing.
 
 If you want access to all of my solutions,
 please write me an email (or contact me in another way),

filter.sh

@@ -4,6 +4,5 @@ set -euo pipefail
 export FILTER_BRANCH_SQUELCH_WARNING=1
 git branch -D filtered
 git switch -c filtered
-git branch -u filtered/filtered
 git filter-branch -f --tree-filter "rm -f $(rg --files-without-match 'SPDX-License-Identifier: (L)?GPL-3.0-or-later' -g '/u??/**/*' | tr '\n' ' ')" HEAD
 git switch -