Update mojo.common.mojom.Value to mojo_base.mojom.Value in mojo.md

Bug: 799482
Change-Id: I925b822f11ac2464ef25cfb77175e9beeb3fa57b
Reviewed-on: https://chromium-review.googlesource.com/1033925
Commit-Queue: Daniel Cheng <[email protected]>
Reviewed-by: Daniel Cheng <[email protected]>
Cr-Commit-Position: refs/heads/master@{#554569}
1 file changed