Minor Getting Started Doc Brush Up

[erikshafer]

Some minor (opinionated) brush ups to the Getting Started guide. Nothing significant.

• Added the missing record for AssignIssue
  • This included adding a region snippet around it and then updating the existing CreateIssue.cs snippet
    • This could be done in the same file, but I left them separate.
• Changed some "I" statements to "We"
• A couple of hyperlinks added
• A few sentences were shortened, and some periods were added.
  • This seems silly, but it can help improve search discovery / Generative AIs write more cohesively. (Whether we want them to or not. 🙃)