Fix asciidoc conversion missing word for #1096.

implementations.adoc

@@ -64,7 +64,7 @@ take effect before the DM returns {abstractcs-busy} to 0.
 To resume execution, the debug module sets a flag which causes the hart
 to execute a `dret`. `dret` is an instruction that only has meaning
 while in Debug Mode and not executing from the Program Buffer. Its
-recommended encoding is 0x7b200073. When `dret` is executed, is restored
+recommended encoding is 0x7b200073. When `dret` is executed, `pc` is restored
 from {csr-dpc} and normal execution resumes at the privilege set by {dcsr-prv} and {dcsr-v},
 and the ELP state set by {dcsr-pelp}.