Rename changemessageInfo to changeMessageInfo
Rename changemessageInfo to changeMessageInfo

In api/gerrit/rest.go. Also, add a comment about these structs.

Bug: 1111112
Change-Id: I8f5822d470ed419b0aae18fc2cd4a22a41e1dded
Reviewed-on: https://chromium-review.googlesource.com/c/infra/luci/luci-go/+/2355626
Reviewed-by: Yiwei Zhang <50b2a565e2e78c292794832469a30ce5abc9959c@google.com>
Commit-Queue: Quinten Yearsley <747cf52e0cef2e3e9371802a2d344b6c87126a4b@chromium.org>

luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go,luci/luci-go