Fixed typo in docs/internals/contributing/triaging-tickets.txt

docs/internals/contributing/triaging-tickets.txt

@@ -448,8 +448,8 @@ Next, we mark the current point in history as being "bad" since the test fails::
 
 Now, we need to find a point in git history before the regression was
 introduced (i.e. a point where the test passes). Use something like
-``git co HEAD~100`` to checkout an earlier revision (100 commits earlier, in
-this case). Check if the test fails. If so, mark that point as "bad"
+``git checkout HEAD~100`` to checkout an earlier revision (100 commits earlier,
+in this case). Check if the test fails. If so, mark that point as "bad"
 (``git bisect bad``), then checkout an earlier revision and recheck. Once you
 find a revision where your test passes, mark it as "good"::