[llvm] [docs] Add beginner-focused office hours (PR #80308)

[Aaron Ballman via llvm-commits]

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@@ -331,6 +331,11 @@ don't find anyone present, chances are they happen to be off that day.
     - Monthly, 4th Wednesday of the month at 9:30am PT, for 30 minutes.
     - `Google meet <https://meet.google.com/pdd-dibg-cwv>`__
     - English
+  * - Rotating hosts
+    - Getting Started, beginner questions, new contributors.
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AaronBallman wrote:

You might want to specify the scope a bit more, like are these focused on LLVM, on Clang, how to use GitHub, or sort of all-of-the-above-plus-more?

https://github.com/llvm/llvm-project/pull/80308