Document increased WriteTimeout as fix in 3.13.1
Created by: mrnugget
I want to ship https://github.com/sourcegraph/sourcegraph/pull/8606 (https://github.com/sourcegraph/sourcegraph/commit/4b038a28a25e7827baa2a31d7abb5871adfa0e4a) in a patch release in 3.13.1.
This documents the change by adding a changelog entry.
I have not yet cherry-picked https://github.com/sourcegraph/sourcegraph/commit/4b038a28a25e7827baa2a31d7abb5871adfa0e4a into 3.13
.