Add missing index references for the `-mrelax' and `-mriscv-attribute'
invocation options.
gcc/
* doc/invoke.texi (RISC-V Options): Add index references for
`mrelax' and `mriscv-attribute'.
@item -mrelax
@itemx -mno-relax
+@opindex mrelax
Take advantage of linker relaxations to reduce the number of instructions
required to materialize symbol addresses. The default is to take advantage of
linker relaxations.
@item -mriscv-attribute
@itemx -mno-riscv-attribute
+@opindex mriscv-attribute
Emit (do not emit) RISC-V attribute to record extra information into ELF
objects. This feature requires at least binutils 2.32.