Auto merge of #4229 - euclio:lint-doc-generation-fix, r=flip1995
Auto merge of #4229 - euclio:lint-doc-generation-fix, r=flip1995

don't strip blank lines in lint documentation

changelog: don't strip blank lines in lint documentation

Fixes #4116.

This PR also switches the docs headings to deterministically display in the order that they are declared in the source, with "Configuration" always appearing last. It doesn't seem like there was a defined order before.

aidancully/rust,aidancully/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,aidancully/rust,graydon/rust,graydon/rust,graydon/rust,graydon/rust,aidancully/rust