APP-7160: viam module update CLI now accepts markdown_link and short_description for models

[michaellee1019]

This PR adds the ability for a developer to further explain the purpose and usage of each model within their module. short_description is a simple text field limited to 100 characters.

markdown_link is a bit more complicated: The link is a relative file path to where the CLI is ran. The purpose is to allow developers to write markdown documentation within their github repo that can be displayed when browsing their respository, and also show this markdown inline within the machine builder on app.viam.com (See the scope document for more details.

The markdown_link can include an anchor tag which links to a specific heading of the markdown content. In this case the content is parse and only the content within that section is consumed for that specific model. This feature allows developers to write a single markdown document for a module containing multiple models, and be able to show just the relevant section for the component/service being used on app.viam.com. In more detail, I've:

• Done research and there does not seem to be a golang markdown parsing library.
• Researched how Github generates anchor tags when you click on header links. And adhered to the same standards. The comments in generateAnchor should explain the rules. LMK if you have questions. The code also ensures that anchors are unique when there are duplicate header names, which Github also does.
• Added tests for the various parsing situations.

In addition to tests I've ran the CLI locally and confirmed that the fields are correctly populated in MongoDB for my test module.

In the future:

• We haven't decided yet if some content types should be stripped. This will be a followup ticket. I think we will likely strip relative images within markdown content and only allow hosted images. Needs more decision before implementing.
• Additional PRs will be done to "encourage" adding these fields. But first we will finish the rest of the project and circle back to the

[michaellee1019]

TY for the fast review!