fixup! [RISCV] RISCV vector calling convention (1/2)

Author: 4vtomat

clang/include/clang/Basic/AttrDocs.td

@@ -5436,6 +5436,7 @@ for clang builtin functions.
 
 def RISCVVectorCCDocs : Documentation {
  let Category = DocCatCallingConvs;
+ let Heading = "riscv::vector_cc, riscv_vector_cc, clang::riscv_vector_cc";
  let Content = [{
 The ``riscv_vector_cc`` attribute can be applied to a function. It preserves 15
 registers namely, v1-v7 and v24-v31 as callee-saved. Callers thus don't need