Update riscv-elf.adoc

Co-authored-by: Jessica Clarke <[email protected]>
Signed-off-by: Rui Ueyama <[email protected]>

Author: rui314

riscv-elf.adoc

@@ -1579,7 +1579,7 @@ NOTE: Tag_RISCV_x3_reg_usage is treated as 0 if it is not present.
 
   Description:: This relaxation can relax a GOT indirection into load
   immediate or PC-relative addressing. This relaxation is intended to
-  optimize the `la`/`lga` assembly pseudo-instruction, which loads a
+  optimize the `lga` assembly pseudo-instruction (and thus `la` for PIC objects), which loads a
   symbol's address from a GOT entry with an `auipc` + `l[w|d]` instruction
   pair.