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

[Pavel Labath 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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labath wrote:

Here I mainly meant the type of dwarf being used (type units, dwo vs. dwp, etc.), though I haven't done some comprehensive tests to know what are all the variables. I don't know how much detail do we want to go in to here. I could change this to "depending on the kind debug info used (type units or not, dwo vs. dwp vs. regular DWARF, ...)", or just omit the part after the comma completely. (I could also omit the entry altogether, but I though people might like to see that)

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