Mainpage fixes

Fix some references to old pages,
 - pattern : "/pages/xxx.html" instead of "/xxx.html", 
 - for example, /pages/governance.html

These pages are mostly only slightly out-of-date, but they no longer exist in this repository, only old versions in the website.
The worst offender was cartopy/pages/documentation.html which dated only to v0.5 (!)

We do **also** need a purge of this stuff... - see https://github.com/SciTools/scitools.org.uk/issues/60

Also removed some non-ASCII quotes + copyrights, for use with simple text editors.