Support subset of Markdown syntax in resource descriptions

[textbook]

User story

• As a user
• I want resource descriptions to support text formatting
• So that I can e.g. highlight the important parts

Supported syntax

The following features will be supported:

• _italic_
• **bold**
• [inline links](url)
• - unordered lists
• 1. ordered lists

However, we don't want users to be able to put e.g. ## headers or arbitrary HTML in their posts.

Acceptance criteria

1. Scenario: User sees supported syntax while suggesting resource

   • Given: a logged-in user
   • When: they visit the draft creation page
   • Then: they are shown information about the supported syntax

2. Scenario: Admin sees rendered output while reviewing suggestion

   • Given: a resource has been suggested using the supported syntax
   • When: an admin reviews it in the drafts list
   • Then: the description is rendered correctly

3. Scenario: User sees rendered output while viewing resources

   • Given: a resource using the supported syntax has been published
   • When: a user reviews it in the resource list
   • Then: the description is rendered correctly

4. Scenario [stretch goal]: User sees rendered output while suggesting resource

   • Given: a resource using is being created
   • When: a user updates the description
   • Then: they are shown the rendered version
   • And: they can check if it is correct

Links

• Markdown - https://daringfireball.net/projects/markdown/
• Stack Overflow comment formatting - https://stackoverflow.com/editing-help#comment-formatting