Update rnmi.adoc

riscv#1626

Signed-off-by: Kersten Richter <[email protected]>

Author: kersten1

src/rnmi.adoc

@@ -32,7 +32,7 @@ in `mtvec` as the RNMI exception trap handler.
 
 === RNMI CSRs
 
-This proposal adds additional M-mode CSRs to enable a resumable
+This extension adds additional M-mode CSRs to enable a resumable
 non-maskable interrupt (RNMI).
 
 .Resumable NMI scratch register `mnscratch`