[clang] [BoundsSafety][doc] Fix a typo (PR #126247)

[LLVM Continuous Integration via cfe-commits]

llvm-ci wrote:

LLVM Buildbot has detected a new failure on builder `clang-aarch64-sve-vla-2stage` running on `linaro-g3-01` while building `clang` at step 12 "ninja check 2".

Full details are available at: https://lab.llvm.org/buildbot/#/builders/41/builds/4907

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

```
Step 12 (ninja check 2) failure: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
...
PASS: lld :: MachO/order-file.s (96468 of 96478)
PASS: lld :: MachO/weak-definition-direct-fetch.s (96469 of 96478)
PASS: lld :: wasm/libsearch.s (96470 of 96478)
PASS: mlgo-utils :: corpus/extract_ir_test.py (96471 of 96478)
PASS: lld :: MachO/loh-adrp-add.s (96472 of 96478)
PASS: lld :: wasm/lto/thinlto.ll (96473 of 96478)
PASS: libFuzzer-aarch64-default-Linux :: value-profile-switch.test (96474 of 96478)
PASS: libFuzzer-aarch64-default-Linux :: strncmp.test (96475 of 96478)
PASS: lld :: MinGW/driver.test (96476 of 96478)
PASS: libFuzzer-aarch64-default-Linux :: value-profile-load.test (96477 of 96478)
command timed out: 1200 seconds without output running [b'ninja', b'check-all'], attempting to kill
process killed by signal 9
program finished with exit code -1
elapsedTime=1811.549114

```

</details>

https://github.com/llvm/llvm-project/pull/126247