Manually update gh-pages at next release

[FWDekker]

The cd.yml workflow introduced in #505 will not automatically import old docs correctly. Some manual work is needed before publishing the release on GitHub:

If the up-to-date gh-pages is in the folder /tmp/gh-pages/ and the main branch is in /tmp/main/, then run

PDIR="/tmp/gh-pages/"
MDIR="/tmp/main/"

cd "$PDIR"
mkdir older/
mv gh-pages/v* older/

cd "$MDIR"
./gradlew -Pdokka.pagesDir="$PDIR"
cd -

rm -rf "$PDIR/"*
mv "$MDIR/build/dokka/html/"* "$PDIR/"

and commit and push the changes in /tmp/gh-pages/ to the gh-pages branch.

[FWDekker]

Fixed in d8515cb.