App Launcher: Remove the period after "Learn more".
App Launcher: Remove the period after "Learn more".

Requested by bettes@.

BUG=576531

Review URL: https://codereview.chromium.org/1845853004

Cr-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#384495}

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