Fix completed-docs rule (#3868)
Fix completed-docs rule (#3868)

- Fixes building of master
- Add escaping to backticks introduced in #3823
JoshuaKGoldberg/tslint,andy-hanson/tslint,palantir/tslint,andy-hanson/tslint,mprobst/tslint,mprobst/tslint,JoshuaKGoldberg/tslint,andy-hanson/tslint,andy-ms/tslint,palantir/tslint,andy-ms/tslint,palantir/tslint,andy-ms/tslint,mprobst/tslint,JoshuaKGoldberg/tslint