[Docs] Fix documentation build.

Missing ending `` after c92ad41

Author: topperc

clang/docs/ReleaseNotes.rst

@@ -458,7 +458,7 @@ LoongArch Support
 RISC-V Support
 ^^^^^^^^^^^^^^
 
-- ``__attribute__((rvv_vector_bits(N))) is now supported for RVV vbool*_t types.
+- ``__attribute__((rvv_vector_bits(N)))`` is now supported for RVV vbool*_t types.
 
 CUDA/HIP Language Changes
 ^^^^^^^^^^^^^^^^^^^^^^^^^