Fix gorouter latency monitor doc link
Fix gorouter latency monitor doc link

The anchor has is all lower-case - fix it.

alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf,alphagov/paas-cf