remove xml to markdown flow and infrastructure

[mjkkirschner]

Purpose

Remove appveyor publish
Remove gitsubmodules
Remove xmlToMarkdownProject (debatable if we want to remove this as part of a cleanup)

Declarations

Check these if you believe they are true

• The code base is in a better state after this PR
• Is documented according to the standards
• The level of testing this PR includes is appropriate
• User facing strings, if any, are extracted into *.resx files
• All tests pass using the self-service CI.
• Snapshot of UI changes, if any.
• Changes to the API follow Semantic Versioning, and are documented in the API Changes document.

Reviewers

@QilongTang
@smangarole
@zeusongit

[QilongTang]

@mjkkirschner I am ok removing XmlDocToMarkdown, I feel like we should redirect to other pages for Dynamo API if we do this cleanly though..

[mjkkirschner]

@QilongTang I will redirect to fuget for now - but removing this code will not bring the site down - so we can do that later if we wish.

[QilongTang]

@mjkkirschner shall we?

[mjkkirschner]

yes, lets see if anything breaks.