* POC of blog post folder
* add parseBlogFileName with tests + refactor and extract processBlogSourceFile in separate method
* improve blog date pattern doc + link from content plugin guides to API ref docs
* Some FrontMatter fields should be able to reference relative image assets, converted to Webpack require calls and exposed as frontMatterAssets
* remove log
* create a swizzleWarning partial for shared text
* Generalize usage of _ prefix convention to exclude content files/folders
* add api doc
* MDX loader should not expect metadata/frontmatter on MDX partial files
* EditUrl function
* normalize blog/docs regarding the editUrl feature + editUrl function
* editUrl fn => always inject posix style relative paths, make tests more reliable
(see also https://github.com/facebook/docusaurus/issues/4124)
* fix editUrl on windows
* stable refactor of plugins api documentation
* plugins sidebar not collapsed by default as small?
* theme docs reorg
* Refactor migration guide doc
* fix broken link
