Move README contents to README.md

Apparently the symlink trick doesn't work like on github so do it this way.
4 jobs for master in 16 minutes and 31 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #209498
build-champlain

00:07:58

passed #209499
build-champlain-gtk

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  Deploy
passed #209500
pages

00:06:59

failed pages:deploy

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