Add pkotwicz@ to chrome/browser/webapps OWNERS

Peter's made a lot of contributions over multiple
years. I think he'd be a valuable OWNER for this
code.

Change-Id: Ia1791868c2bec8aa234b21facd8718080fdfc6d4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1721831Reviewed-by: Dominick Ng <dominickn@chromium.org>
Commit-Queue: Peter Kotwicz <pkotwicz@chromium.org>
Cr-Commit-Position: refs/heads/master@{#681834}

chrome/android/java/src/org/chromium/chrome/browser/webapps/OWNERS

@@ -2,5 +2,6 @@ dominickn@chromium.org
 mlamouri@chromium.org
 peconn@chromium.org
 peter@chromium.org
+pkotwicz@chromium.org
 
 # COMPONENT: UI>Browser>WebAppInstalls