runtime: fix code span element

Change-Id: I99c593573b3bec560ab3af49ac2f486ee442ee1c
GitHub-Last-Rev: e399ec5
GitHub-Pull-Request: #52946
Reviewed-on: https://go-review.googlesource.com/c/go/+/406837
TryBot-Result: Gopher Robot <[email protected]>
Reviewed-by: Michael Knyszek <[email protected]>
Reviewed-by: Ian Lance Taylor <[email protected]>
Run-TryBot: Ian Lance Taylor <[email protected]>
Auto-Submit: Michael Knyszek <[email protected]>

Author: jbampton

src/runtime/HACKING.md

@@ -97,7 +97,7 @@ For runtime error debugging, it may be useful to run with `GOTRACEBACK=system`
 or `GOTRACEBACK=crash`. The output of `panic` and `fatal` is as described by
 `GOTRACEBACK`. The output of `throw` always includes runtime frames, metadata
 and all goroutines regardless of `GOTRACEBACK` (i.e., equivalent to
-`GOTRACEBACK=system). Whether `throw` crashes or not is still controlled by
+`GOTRACEBACK=system`). Whether `throw` crashes or not is still controlled by
 `GOTRACEBACK`.
 
 Synchronization