[llvm] [llvm] Proofread MergeFunctions.rst (PR #166317)

[LLVM Continuous Integration via llvm-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `ppc64le-mlir-rhel-clang` running on `ppc64le-mlir-rhel-test` while building `llvm` at step 6 "test-build-check-mlir-build-only-check-mlir".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/129/builds/32415

<details>
<summary>Here is the relevant piece of the build log for the reference</summary>

```
Step 6 (test-build-check-mlir-build-only-check-mlir) failure: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
...
PASS: MLIR-Unit :: IR/./MLIRIRTests/0/130 (3622 of 3633)
PASS: MLIR-Unit :: IR/./MLIRIRTests/39/130 (3623 of 3633)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/12/22 (3624 of 3633)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/13/22 (3625 of 3633)
PASS: MLIR-Unit :: IR/./MLIRIRTests/38/130 (3626 of 3633)
PASS: MLIR-Unit :: Interfaces/./MLIRInterfacesTests/11/22 (3627 of 3633)
PASS: MLIR-Unit :: Pass/./MLIRPassTests/10/13 (3628 of 3633)
PASS: MLIR :: Pass/pipeline-parsing.mlir (3629 of 3633)
PASS: MLIR :: Pass/pipeline-options-parsing.mlir (3630 of 3633)
PASS: MLIR :: mlir-reduce/dce-test.mlir (3631 of 3633)
command timed out: 1200 seconds without output running [b'ninja', b'check-mlir'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=2479.198742

```

</details>

https://github.com/llvm/llvm-project/pull/166317