Remove singlehtml builds (#2747)

Singlehtml pages are rarely used, but publishing them increases build time and requires extra support effort.

Author: NickVolynkin

.github/workflows/main.yml

@@ -32,8 +32,6 @@ jobs:
       - run: make build-modules
       - run: make json
       - run: make json-ru
-      - run: make singlehtml
-      - run: make singlehtml-ru
       - run: make pdf
       - run: make pdf-ru
       - uses: nelonoel/[email protected]