`master` broken in `docs lint`

Job #469481360 failed for 0a06be7d:

37 $ scripts/lint-doc.sh
38 => Linting documents at path /builds/gitlab-org/gitlab as root...
39 => Checking for cURL short options...
40 => Checking for CHANGELOG.md duplicate entries...
41 => Checking /builds/gitlab-org/gitlab/doc for executable permissions...
42 => Checking for new README.md files...
43 => Linting markdown style...
44 => Linting prose...
45  doc/administration/high_availability/README.md
46  33:3  error  Link [Installation                                         gitlab.InternalLinkExtension 
47               Docs](../../install/README.html)                                                        
48               must use the .md file extension.                                                        
49  71:3  error  Link [GitLab Geo with a highly available                   gitlab.InternalLinkExtension 
50               configuration](../geo/replication/high_availability.html)                               
51               must use the .md file extension.                                                        
52 ✖ 2 errors, 0 warnings and 0 suggestions in 1328 files.
53   ✖ ERROR: 'vale' failed with errors.