Merge branch 'kh/doc-trailers' into jch

Documentation for 'git interpret-trailers' has been updated to explain the format of trailer keys (alphanumeric characters and hyphens), replace outdated terminology, define key terms upfront, and document how comment lines in the input are treated. * kh/doc-trailers: doc: interpret-trailers: document comment line treatment doc: interpret-trailers: rewrite new-trailers paragraphs doc: interpret-trailers: commit to “trailer block” term doc: interpret-trailers: join new-trailers again doc: interpret-trailers: add key format example doc: interpret-trailers: explain key format doc: interpret-trailers: explain the format after the intro doc: interpret-trailers: not just for commit messages doc: interpret-trailers: use “metadata” in Name as well doc: interpret-trailers: replace “lines” with “metadata” doc: interpret-trailers: stop fixating on RFC 822