Add Jerop as an owner 🎉

@jerop has been reviewed 32 PRs in pipelines
(https://github.com/tektoncd/pipeline/pulls?q=is%3Apr+reviewed-by%3Ajerop+-author%3Ajerop)
and has authored 27 PRs against this repo (https://github.com/tektoncd/pipeline/pulls/jerop)
including when expressions #3135,
in addition to making significant improvements to our processes
(e.g. defining design principles tektoncd/community#171
and recently proposing topical areas of ownership)

Thanks for all your hard work @jerop!!

OWNERS_ALIASES

@@ -8,6 +8,7 @@ aliases:
   - sbwsg
   - vdemeester
   - pritidesai
+  - jerop
 
   apis-approvers:
   - afrittoli
@@ -18,6 +19,7 @@ aliases:
   - sbwsg
   - vdemeester
   - pritidesai
+  - jerop
 
   productivity-approvers:
   - afrittoli