[clang] [docs][coroutines] Update gdb debugger script (PR #162145)

[Kazu Hirata via cfe-commits]

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@@ -1019,154 +1016,273 @@ GDB Debugger Script
 
 For GDB, the following script provides a couple of useful commands:
 
-* ``async-bt`` to print the stack trace of a coroutine
-* ``show-coro-frame`` to print the coroutine frame, similar to
-  LLDB's builtin pretty-printer for coroutine frames
+The following script provides
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kazutakahirata wrote:

```suggestion
The following script provides:
```

https://github.com/llvm/llvm-project/pull/162145