[llvm] [llvm][Docs] Add a release note about the lldb DWARF indexing speedup (PR #122870)

[David Spickett via llvm-commits]

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@@ -449,6 +449,8 @@ Changes to LLDB
           _regexp-bt        -- Show backtrace of the current thread's call ...
           _regexp-display   -- Evaluate an expression at every stop (see 'h...
   ```
+* DWARF indexing speed (for binaries not using the debug_names index) increased
+  by 30-60%, depending on the configuration.
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DavidSpickett wrote:

I imagine a reader who thinks this is cool but wonders if they can get even more of a speedup. There are probably < 5 people and 3 of them are you and your reviewers but who knows.

To keep it brief, you could remove the bit after the comma and link to the PRs instead, or to the single, key PR. They have all the detail anyone could possibly want.

https://github.com/llvm/llvm-project/pull/122870