Remove Pawoo apps from README.md
Pawoo's iOS/Android apps are deprecated. See also https://pawoo.net/users/pixiv/statuses/100960929076229958 and https://source.joinmastodon.org/mastodon/joinmastodon/merge_requests/32.
Pawoo's iOS/Android apps are deprecated. See also https://pawoo.net/users/pixiv/statuses/100960929076229958 and https://source.joinmastodon.org/mastodon/joinmastodon/merge_requests/32.