[lldb] Add a page to the documentation with (external) links on how to use LLDB

[JDevlieghere]

Summary

In a discussion with Jim last week we came to the realization that often we get asked about things that might not be documented on the website, but that have been pretty well explained elsewhere. In those situations it's often easier to quickly answer the question than searching for that presentation you gave 3 years ago if you remember at all. This often results in us having to answer the same questions over and over again. We could add the questions and their answer to the website, but that means we (1) have to duplicate the work and (2) now have to maintain it. A more efficient solution is to add a page with external resources with the caveat that they might be outdated. That's exactly the purpose of this patch.

I've added a few links that came to mind, but I don't want to be the arbiter of what should and should not be included. I'd hope that over time the community can crowdsource the best resources.

[vsk]

+ 1, this looks good to me.

I think there might be room to include a short (~1 sentence) summary next to each extension entry, so readers know what to expect before clicking on one.

[JDevlieghere]

• Use markdown
• Add a little text snippet to the links

lldb/docs/index.rst

.. toctree::
    use/variable
    use/symbolication
    use/symbols
    use/python
    use/python-reference
    use/remote
    use/qemu-testing
    use/troubleshooting
+   use/links
 
 .. toctree::
    :hidden:
    :maxdepth: 1
    :caption: Development
 
    resources/contributing
    resources/build

lldb/docs/use/links.md

+Links
+=====
+
+This page contains links to external resources on how to use LLDB. Being listed
+on this page is not an endorsement.
+
+## Blog Posts
+
+### [Dancing in the Debugger — A Waltz with LLDB (2014) ](https://www.objc.io/issues/19-debugging/lldb-debugging/)
+
+A high level overview of LLDB with a focus on debugging Objective-C code.
+
+## Videos
+
+### [LLDB: Beyond "po" (2019)](https://developer.apple.com/videos/play/wwdc2019/429/)
+
+LLDB is a powerful tool for exploring and debugging your app at runtime.
+Discover the various ways to display values in your app, how to format custom
+data types, and how to extend LLDB using your own Python 3 scripts.
+
+### [Advanced Debugging with Xcode and LLDB (2018)](https://developer.apple.com/videos/play/wwdc2018/412/)
+
+Discover advanced techniques, and tips and tricks for enhancing your Xcode
+debugging workflows. Learn how to take advantage of LLDB and custom breakpoints
+for more powerful debugging. Get the most out of Xcode's view debugging tools
+to solve UI issues in your app more efficiently.
+
+### [Debugging with LLDB (2012)](https://developer.apple.com/videos/play/wwdc2012/415/)
+
+LLDB is the next-generation debugger for macOS and iOS. Get an introduction to
+using LLDB via the console interface and within Xcode's graphical debugger. The
+team that created LLDB will demonstrate the latest features and improvements,
+helping you track down bugs more efficiently than ever before.
+
+### [Migrating from GDB to LLDB (2011)](https://developer.apple.com/videos/play/wwdc2011/321/)
+
+LLDB is the next-generation debugger for macOS and iOS. Discover why you'll
+want to start using LLDB in your own development, get expert tips from the team
+that created LLDB, and see how it will help you track down bugs more
+efficiently than ever before.
+
+## Books
+
+### [Advanced Apple Debugging & Reverse Engineering (2018)](https://www.raywenderlich.com/books/advanced-apple-debugging-reverse-engineering/)
+
+A book about using LLDB on Apple platforms.
+
+## Extensions
+
+### [facebook/chisel](https://github.com/facebook/chisel)
+
+Chisel is a collection of LLDB commands to assist in the debugging of iOS apps.
+
+### [DerekSelander/LLDB](https://github.com/DerekSelander/LLDB)
+
+A collection of LLDB aliases/regexes and Python scripts.