[Clang][Doc] Add release note for changes for the RVV intrinsics

Reviewed By: asb

Differential Revision: https://reviews.llvm.org/D142094

Author: eopXD

clang/docs/ReleaseNotes.rst

@@ -881,6 +881,17 @@ RISC-V Support in Clang
   take architecture extensions from ``-march`` if both are given.
 - An ABI mismatch between GCC and Clang that related to the
   sign/zero-extension of integer scalars was fixed.
+- An overall simplification of the RISC-V Vector intrinsics are done. The
+  simplification is based on
+  `riscv-non-isa/rvv-intrinsic-doc#186 <https://github.com/riscv-non-isa/rvv-intrinsic-doc/pull/186>`_.
+- Intrinsics of `vcompress` and `vmerge` have been adjusted to have interfaces
+  be aligned among `vvm`, `vxm` intrinsics. The adjustment is base on
+  `riscv-non-isa/rvv-intrinsic-doc#185 <https://github.com/riscv-non-isa/rvv-intrinsic-doc/pull/185>`_.
+- All RISC-V Vector intrinsics now share a `__riscv_` prefix, based on the
+  naming convention defined by
+  `riscv-non-isa/riscv-c-api-doc#31 <https://github.com/riscv-non-isa/riscv-c-api-doc/pull/31>`_.
+- Note that the RISC-V Vector C intrinsics are still under development. The RVV
+  C Intrinsic Task Group is working towards a ratified v1.0.
 
 X86 Support in Clang
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