Create start-posting-notes.md

[boston-wine]

Re-do on creating the "Start Posting Notes" page. Closed the old PR, synced to your current repo.

I think this is right, now, as the only difference between my fork and your original is this page.

Let me know if I should update the sidebar like you had mentioned on the old PR. If so, I found where to add the page to the sidebar, but was not sure how I should edit the line that identifies the page. Each menu item is formatted like this:

{ href: "/guides/setup-zapping-wallet", localeString: "nav.guideSetupWallet" }, So presumably, mine should look something like this, but I'm not clear on what the text at the end should actually say, or if I need to define it elsewhere (like on the actual Start Posting Notes page).

{ href: "/guides/start-posting-notes", localeString: "nav.guide__?_?_?__" },

Anyway, if it makes no difference to you, @erskingardner, it's probably simpler for me to learn/cement the PR process by just working on this page by itself, and then making a separate, second change to update the sidebar nav, so that I get the practice with syncing, forking, editing, and opening pull requests.

Oh, and let me know if you'd advise any changes to the copy itself 🫡