Add app links to README.md (#1340)
Add app links to README.md (#1340)

Add app links to README.md (implements #1338)
vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,kunall17/zulip-mobile,kunall17/zulip-mobile,vishwesh3/zulip-mobile,kunall17/zulip-mobile,kunall17/zulip-mobile,vishwesh3/zulip-mobile