[llvm] [Docs] Update contribution guide to remove the single-commit requirement (PR #212031)

[via llvm-commits]

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@@ -28,9 +28,15 @@ let people know you are working on it.
 
 Then try to reproduce and fix the bug with upstream LLVM. Start by building
 LLVM from source as described in {doc}`GettingStarted` and
-use the built binaries to reproduce the failure described in the bug. Use
-a debug build (`-DCMAKE_BUILD_TYPE=Debug`) or a build with assertions
-(`-DLLVM_ENABLE_ASSERTIONS=On`, enabled for Debug builds).
+use the built binaries to reproduce the failure described in the bug.
+
+Use a Release build (`-DCMAKE_BUILD_TYPE=Release`) with assertions (`-DLLVM_ENABLE_ASSERTIONS=On`).
+If you want to build LLVM in Debug mode (`-DCMAKE_BUILD_TYPE=Debug`) instead, consider using
+`-DLLVM_PARALLEL_LINK_JOBS=number` and set the linker to anything other than GNU `ld`
+(e.g. `lld` or `mold`, by passing `-DLLVM_USE_LINKER=lld` or `-DLLVM_USE_LINKER=mold`);
+otherwise, you'll likely run out of memory unless you have a lot of RAM.
+
+See also {doc}`CMake` for more information about how to build LLVM.
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zhangweize9-cyber wrote:

Seems good to me. I think it would be better if you added a specific line number jump link to the introductory guide.

https://github.com/llvm/llvm-project/pull/212031