[llvm][docs] Improve usage note on stacked PRs

[paschalis-mpeis]

No description provided.

[paschalis-mpeis]

Just realized I forgot to update the note references in #138126.
I just did this, with a few more proposed changes.

Any thoughts?

[banach-space]

Thank you, LGTM!

[llvm-ci]

LLVM Buildbot has detected a new failure on builder lldb-x86_64-debian running on lldb-x86_64-debian while building llvm at step 6 "test".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/162/builds/22532

Here is the relevant piece of the build log for the reference

Step 6 (test) failure: build (failure)
...
PASS: lldb-api :: functionalities/data-formatter/data-formatter-stl/generic/deque/TestDataFormatterGenericDeque.py (97 of 2937)
PASS: lldb-api :: commands/expression/ir-interpreter/TestIRInterpreter.py (98 of 2937)
PASS: lldb-api :: commands/watchpoints/multiple_threads/TestWatchpointMultipleThreads.py (99 of 2937)
PASS: lldb-api :: tools/lldb-server/vCont-threads/TestPartialResume.py (100 of 2937)
PASS: lldb-api :: commands/expression/no-deadlock/TestExprDoesntBlock.py (101 of 2937)
PASS: lldb-api :: python_api/module_section/TestModuleAndSection.py (102 of 2937)
PASS: lldb-api :: tools/lldb-dap/variables/children/TestDAP_variables_children.py (103 of 2937)
PASS: lldb-api :: tools/lldb-dap/coreFile/TestDAP_coreFile.py (104 of 2937)
PASS: lldb-api :: functionalities/return-value/TestReturnValue.py (105 of 2937)
UNRESOLVED: lldb-api :: tools/lldb-dap/evaluate/TestDAP_evaluate.py (106 of 2937)
******************** TEST 'lldb-api :: tools/lldb-dap/evaluate/TestDAP_evaluate.py' FAILED ********************
Script:
--
/usr/bin/python3 /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/dotest.py -u CXXFLAGS -u CFLAGS --env LLVM_LIBS_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/./lib --env LLVM_INCLUDE_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/include --env LLVM_TOOLS_DIR=/home/worker/2.0.1/lldb-x86_64-debian/build/./bin --arch x86_64 --build-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex --lldb-module-cache-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/module-cache-lldb/lldb-api --clang-module-cache-dir /home/worker/2.0.1/lldb-x86_64-debian/build/lldb-test-build.noindex/module-cache-clang/lldb-api --executable /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/lldb --compiler /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/clang --dsymutil /home/worker/2.0.1/lldb-x86_64-debian/build/./bin/dsymutil --make /usr/bin/gmake --llvm-tools-dir /home/worker/2.0.1/lldb-x86_64-debian/build/./bin --lldb-obj-root /home/worker/2.0.1/lldb-x86_64-debian/build/tools/lldb --lldb-libs-dir /home/worker/2.0.1/lldb-x86_64-debian/build/./lib -t /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/tools/lldb-dap/evaluate -p TestDAP_evaluate.py
--
Exit Code: 1

Command Output (stdout):
--
lldb version 21.0.0git (https://github.com/llvm/llvm-project.git revision bb5566aac2f236d49c74ce3c53b5c832f4d9a22b)
  clang revision bb5566aac2f236d49c74ce3c53b5c832f4d9a22b
  llvm revision bb5566aac2f236d49c74ce3c53b5c832f4d9a22b
Skipping the following test categories: ['libc++', 'dsym', 'gmodules', 'debugserver', 'objc']

--
Command Output (stderr):
--
Change dir to: /home/worker/2.0.1/lldb-x86_64-debian/llvm-project/lldb/test/API/tools/lldb-dap/evaluate
runCmd: settings clear --all

output: 

runCmd: settings set symbols.enable-external-lookup false

output: 

runCmd: settings set target.inherit-tcc true

output: 

runCmd: settings set target.disable-aslr false

output: 

runCmd: settings set target.detach-on-error false

output: 

runCmd: settings set target.auto-apply-fixits false