[clang] [ASTMatchers][NFC] improve 'isInteger' docs to show matching of unsigned (PR #147012)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `flang-arm64-windows-msvc` running on `linaro-armv8-windows-msvc-01` while building `clang` at step 7 "test-build-unified-tree-check-flang".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/207/builds/3387

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

```
Step 7 (test-build-unified-tree-check-flang) failure: test (failure)
******************** TEST 'Flang :: Lower/OpenMP/wsloop-reduction-logical-kinds.f90' FAILED ********************
Exit Code: 2

Command Output (stdout):
--
# RUN: at line 1
c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe -fc1 -emit-hlfir -fopenmp -o - C:\Users\tcwg\llvm-worker\flang-arm64-windows-msvc\llvm-project\flang\test\Lower\OpenMP\wsloop-reduction-logical-kinds.f90 | c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\filecheck.exe C:\Users\tcwg\llvm-worker\flang-arm64-windows-msvc\llvm-project\flang\test\Lower\OpenMP\wsloop-reduction-logical-kinds.f90
# executed command: 'c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe' -fc1 -emit-hlfir -fopenmp -o - 'C:\Users\tcwg\llvm-worker\flang-arm64-windows-msvc\llvm-project\flang\test\Lower\OpenMP\wsloop-reduction-logical-kinds.f90'
# .---command stderr------------
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
# | Stack dump:
# | 0.	Program arguments: c:\\users\\tcwg\\llvm-worker\\flang-arm64-windows-msvc\\build\\bin\\flang.exe -fc1 -emit-hlfir -fopenmp -o - C:\\Users\\tcwg\\llvm-worker\\flang-arm64-windows-msvc\\llvm-project\\flang\\test\\Lower\\OpenMP\\wsloop-reduction-logical-kinds.f90
# | Exception Code: 0xC0000005
# |  #0 0x00007ff6b6c222a0 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x1a922a0)
# |  #1 0x00007ff6b6c1ff88 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x1a8ff88)
# |  #2 0x00007ff6b6c1de1c (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x1a8de1c)
# |  #3 0x00007ff6b6c23b30 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x1a93b30)
# |  #4 0x00007ff6b6c1d984 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x1a8d984)
# |  #5 0x00007ff6b5a3cb40 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x8acb40)
# |  #6 0x00007ff6b5a85fa0 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x8f5fa0)
# |  #7 0x00007ff6b5b2f3e4 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x99f3e4)
# |  #8 0x00007ff6b5a853dc (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x8f53dc)
# |  #9 0x00007ff6b5228ac8 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x98ac8)
# | #10 0x00007ff6b523ea90 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0xaea90)
# | #11 0x00007ff6b51934e8 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x34e8)
# | #12 0x00007ff6b51920a4 (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x20a4)
# | #13 0x00007ff6b9e50560 mlir::detail::FallbackTypeIDResolver::registerImplicitTypeID(class llvm::StringRef) (c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\flang.exe+0x4cc0560)
# | #14 0xc8297ff6b9e505fc
# `-----------------------------
# error: command failed with exit status: 0xc0000005
# executed command: 'c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\filecheck.exe' 'C:\Users\tcwg\llvm-worker\flang-arm64-windows-msvc\llvm-project\flang\test\Lower\OpenMP\wsloop-reduction-logical-kinds.f90'
# .---command stderr------------
# | FileCheck error: '<stdin>' is empty.
# | FileCheck command line:  c:\users\tcwg\llvm-worker\flang-arm64-windows-msvc\build\bin\filecheck.exe C:\Users\tcwg\llvm-worker\flang-arm64-windows-msvc\llvm-project\flang\test\Lower\OpenMP\wsloop-reduction-logical-kinds.f90
# `-----------------------------
# error: command failed with exit status: 2

--

********************


```

</details>

https://github.com/llvm/llvm-project/pull/147012