remove extra name

Author: realqhc

llvm/docs/RISCVUsage.rst

@@ -335,7 +335,7 @@ The primary goal of experimental support is to assist in the process of ratifica
 ``experimental-svukte``
   LLVM implements the `0.3 draft specification <https://github.com/riscv/riscv-isa-manual/pull/1564>`__.
 
-``experimental-p``, ``experimental-p``
+``experimental-p``
   LLVM implements the `014 draft specification <https://jhauser.us/RISCV/ext-P/RVP-baseInstrs-014.pdf>`__.
 
 To use an experimental extension from `clang`, you must add `-menable-experimental-extensions` to the command line, and specify the exact version of the experimental extension you are using.  To use an experimental extension with LLVM's internal developer tools (e.g. `llc`, `llvm-objdump`, `llvm-mc`), you must prefix the extension name with `experimental-`.  Note that you don't need to specify the version with internal tools, and shouldn't include the `experimental-` prefix with `clang`.