Fixed links and page title

 Update page title with header value for each page
 Re-enabled converting XWALK-channel-platform-arch in pages to correct value
 Added Release 9 to download release notes section
 Fixed all reported missing link bugs

 BUG = XWALK-828
 BUG = XWALK-2827
 BUG = XWALK-2816
 BUG = XWALK-2817
 BUG = XWALK-2824
 BUG = XWALK-2825
 BUG = XWALK-2828
 BUG = XWALK-2826
Merge branch 'fix-doc-links'