fix redirect url and redirect from 5.2 onwards (#110)

* Update redirect logic to redirect versions ≥ 5.2 to new docs domain

* Update redirect URL to use @Version format

set GOFLAGS on release

site: keep expired cache when background refresh failed (#100)

[docsite]: fix error page if template not exists (#98)

Fixes for Preview URL Redirects, CSS Asset Fetching, and Post-Merge P…

…review URL Availability (#96)

markdown: really fix soft line break rendering (#95)

markdown: support soft-line breaks (#92)

chore: refurbish CI setup (#90)

Make rel links checker more precise. (#85)

Co-authored-by: William Bezuidenhout <william.bezuidenhout+github@gmail.com>

Remove content documents from search index