Merge pull request progit#1564 from progit/check_epub

Merge pull request progit#1563 from yugaego/format

Merge pull request progit#1300 from max123kl/patch-1

Line 229 formatting error by * (asterisk) fixed

Merge pull request progit#1561 from ixth/patch-1

Escape tilde to fix HEAD~~~ presented as HEAD~

Merge pull request progit#1539 from Sophismata/issue-1358

Merge pull request progit#1560 from progit/dependabot/bundler/asciido…

…ctor-2.0.12

Update asciidoctor requirement from 2.0.11 to 2.0.12

Merge pull request progit#1389 from slonopotamus/patch-1

Stop adding negative leveloffset for EPUB

Merge pull request progit#1554 from HonkingGoose/migration-asciidocto…

…r-2.0.11

Migrate to Asciidoctor 2.0.11

Merge pull request progit#1545 from stuartpb/patch-1

Merge pull request progit#1544 from ardavast/fix-typo

Fix typo in section 2.4