* chore(docs): apply some linting * chore(docs): add markdownlint and cpell config files * remove duplicate key * add extension recommendation * update cspell
* chore(apps): move icons into the apps folder * rename to `icon.png` * replace solr image * remove `docs/` from gitignore * move app specific docs into app folder [skip ci] * fix some links * chore(apps): update image links temporary