Add yoichio@ to WebSocket OWNERS

Yoichi landed many CLs for https://crbug.com/865001 and
https://crbug.com/967524 and I think it's good to have him as an OWNER.

Bug: None
Change-Id: I5e3b8d9b362a18d53cdca383cc1c61a9b3beb993
No-Try: True
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2086389
Commit-Queue: Yoichi Osato <yoichio@chromium.org>
Auto-Submit: Yutaka Hirano <yhirano@chromium.org>
Reviewed-by: Yoichi Osato <yoichio@chromium.org>
Reviewed-by: Adam Rice <ricea@chromium.org>
Cr-Commit-Position: refs/heads/master@{#747174}

net/websockets/OWNERS

 ricea@chromium.org
 yhirano@chromium.org
+yoichio@chromium.org
 
 # TEAM: blink-network-dev@chromium.org
 # COMPONENT: Blink>Network>WebSockets

third_party/blink/renderer/modules/websockets/OWNERS

 ricea@chromium.org
 yhirano@chromium.org
+yoichio@chromium.org
 
 # TEAM: blink-network-dev@chromium.org
 # COMPONENT: Blink>Network>WebSockets