Update mfpub for current MarlinDocumentation

buildroot/share/git/mfpub

 echo
 echo "Generating MarlinDocumentation..."
 
-rm -rf _site
+rm -rf build
 
 # build the site statically and proof it
 bundle exec jekyll build --profile --trace --no-watch
-bundle exec htmlproofer ./_site --only-4xx --allow-hash-href --check-favicon --check-html --url-swap ".*marlinfw.org/:/"
+bundle exec htmlproofer ./build --only-4xx --allow-hash-href --check-favicon --check-html --url-swap ".*marlinfw.org/:/"
 
 # Sync the built site into a temporary folder
 TMPFOLDER=$( mktemp -d )
-rsync -av _site/ ${TMPFOLDER}/
+rsync -av build/ ${TMPFOLDER}/
 
 # Clean out changes and other junk in the branch
 git reset --hard