LPS-37884 added liferay community stream to default RSS feeds

as documented in https://issues.liferay.com/browse/LPS-37884 and communicated with Product Management:

Adding community blog stream as number 1
Changing number of entries from 8 to 4 - this commit looks like it's changed from 2 to 4: That's due to items-per-channel having been inactive/unused, thus RSS feeds always defaulted to 8