* Fixing most of remaining bad links
Still left :
#google.rpc.Code in reference/api/mixer/status
And the mixer-config-quota-bookinfo.yaml is missing in
https://github.com/istio/istio/tree/master/samples/apps/bookinfo
* Add html checking and ignore localhost urls
fixed typo in layouts/base found by html checking
* Fix duplicate id defined
Those anchors don’t seem used btw
* Adding back html proofer
got removed accidentally it seems
* Fix the last 2 errors