XWIKI-9673: Main wiki descriptor page XWiki.XWikiServerXwiki is missing after Wiki Manager installation.
Merge branch 'master' into XWIKI-9673
XWIKI-9673: Main wiki descriptor page XWiki.XWikiServerXwiki is missing after Wiki Manager installation.

* Fix HTML violation
XWIKI-9673: Main wiki descriptor page XWiki.XWikiServerXwiki is missing after Wiki Manager installation.

* Fix HTML violation
Merge pull request #252 from gdelhumeau/XWIKI-9673

XWIKI-9673: Main wiki descriptor page XWiki.XWikiServerXwiki is missing after Wiki Manager installation
* Fix HTML validation issues