Update links for page layout after conversion from mediawiki
Rewrite links using our `link-rewrite.sed` script:
git ls-files | xargs sed -i -f link-rewrite.sed
Organize page layout after conversion from mediawiki
Organize pages into directories and shorter file names. Use lower-case
names for directories and capitalized names for files. This produces a
pleasing sort order in the GitLab Wiki navigation page.
Also rename entry page `CMake.md` to `Home.md` to match GitLab Wiki
conventions.
