Removed the mention of onUpdated event as it doesn't exist in doc explanation

Signed-off-by: Shwetank Dixit <emailshwetank@gmail.com>
Sample extensions for Omnibox extensions

Signed-off-by: Shwetank Dixit <emailshwetank@gmail.com>
Image for omnibox extension article

Signed-off-by: Shwetank Dixit <emailshwetank@gmail.com>
Omnibox extension article

Signed-off-by: Shwetank Dixit <emailshwetank@gmail.com>
Merge pull request #59 from shwetank/master

Omnibox article and small cleanup of stash api doc