Update README.md (#2655)
Update README.md (#2655)

Add the second QQ group number.
apache/skywalking,ascrutae/sky-walking,OpenSkywalking/skywalking,apache/skywalking,apache/skywalking,apache/skywalking,apache/skywalking,apache/skywalking,ascrutae/sky-walking,ascrutae/sky-walking,OpenSkywalking/skywalking,apache/skywalking,ascrutae/sky-walking