[Docs] Add information on release management
[Docs] Add information on release management

R=1cf0af8245a3a17a632a2c73531392b0f9761c76@chromium.org
BUG=1021467

Change-Id: If1f354d4cbdc9153964804980d17dba2883da1c6
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/1928918
Auto-Submit: Michael Hablich <738c2fdc53f8b1553cee5c6a41ce003a6bb57f69@chromium.org>
Reviewed-by: Yang Guo <1cf0af8245a3a17a632a2c73531392b0f9761c76@chromium.org>
Commit-Queue: Michael Hablich <738c2fdc53f8b1553cee5c6a41ce003a6bb57f69@chromium.org>

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