Add `markdownlint` linter and fix issues. Config is based on the one
from electron's repo with a few rules relaxed.

* Fix various typos

Found via `codespell -q 3 -S ./options/locale,./options/license,./public/vendor -L actived,allways,attachements,ba,befores,commiter,pullrequest,pullrequests,readby,splitted,te,unknwon`

Co-authored-by: zeripath <art27@cantab.net>

* Add version hint in the docs when packages are available

* Change italic to bold

* Improve package registry docs

* move new content down

* add hint re upload a package

* wording, formatting

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

* Added package store settings.

* Added models.

* Added generic package registry.

* Added tests.

* Added NuGet package registry.

* Moved service index to api file.

* Added NPM package registry.

* Added Maven package registry.

* Added PyPI package registry.

* Summary is deprecated.

* Changed npm name.

* Sanitize project url.

* Allow only scoped packages.

* Added user interface.

* Changed method name.

* Added missing migration file.

* Set page info.

* Added documentation.

* Added documentation links.

* Fixed wrong error message.

* Lint template files.

* Fixed merge errors.

* Fixed unit test storage path.

* Switch to json module.

* Added suggestions.

* Added package webhook.

* Add package api.

* Fixed swagger file.

* Fixed enum and comments.

* Fixed NuGet pagination.

* Print test names.

* Added api tests.

* Fixed access level.

* Fix User unmarshal.

* Added RubyGems package registry.

* Fix lint.

* Implemented io.Writer.

* Added support for sha256/sha512 checksum files.

* Improved maven-metadata.xml support.

* Added support for symbol package uploads.

* Added tests.

* Added overview docs.

* Added npm dependencies and keywords.

* Added no-packages information.

* Display file size.

* Display asset count.

* Fixed filter alignment.

* Added package icons.

* Formatted instructions.

* Allow anonymous package downloads.

* Fixed comments.

* Fixed postgres test.

* Moved file.

* Moved models to models/packages.

* Use correct error response format per client.

* Use simpler search form.

* Fixed IsProd.

* Restructured data model.

* Prevent empty filename.

* Fix swagger.

* Implemented user/org registry.

* Implemented UI.

* Use GetUserByIDCtx.

* Use table for dependencies.

* make svg

* Added support for unscoped npm packages.

* Add support for npm dist tags.

* Added tests for npm tags.

* Unlink packages if repository gets deleted.

* Prevent user/org delete if a packages exist.

* Use package unlink in repository service.

* Added support for composer packages.

* Restructured package docs.

* Added missing tests.

* Fixed generic content page.

* Fixed docs.

* Fixed swagger.

* Added missing type.

* Fixed ambiguous column.

* Organize content store by sha256 hash.

* Added admin package management.

* Added support for sorting.

* Add support for multiple identical versions/files.

* Added missing repository unlink.

* Added file properties.

* make fmt

* lint

* Added Conan package registry.

* Updated docs.

* Unify package names.

* Added swagger enum.

* Use longer TEXT column type.

* Removed version composite key.

* Merged package and container registry.

* Removed index.

* Use dedicated package router.

* Moved files to new location.

* Updated docs.

* Fixed JOIN order.

* Fixed GROUP BY statement.

* Fixed GROUP BY #2.

* Added symbol server support.

* Added more tests.

* Set NOT NULL.

* Added setting to disable package registries.

* Moved auth into service.

* refactor

* Use ctx everywhere.

* Added package cleanup task.

* Changed packages path.

* Added container registry.

* Refactoring

* Updated comparison.

* Fix swagger.

* Fixed table order.

* Use token auth for npm routes.

* Enabled ReverseProxy auth.

* Added packages link for orgs.

* Fixed anonymous org access.

* Enable copy button for setup instructions.

* Merge error

* Added suggestions.

* Fixed merge.

* Handle "generic".

* Added link for TODO.

* Added suggestions.

* Changed temporary buffer filename.

* Added suggestions.

* Apply suggestions from code review

Co-authored-by: Thomas Boerger <thomas@webhippie.de>

* Update docs/content/doc/packages/nuget.en-us.md

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>
Co-authored-by: Thomas Boerger <thomas@webhippie.de>