doc : update flat-ui to v1.2.1

Plus correcting name folder
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/master' into gh-pages
Merge remote-tracking branch 'origin/gh-pages'