Add release 2.6.2 version docs (#8489)
Add release 2.6.2 version docs (#8489)

Signed-off-by: xiaolong.ran <7d13e43fbbc3fc16d27e460280d19c5113a24274@apache.org>

### Motivation

Add release 2.6.2 version docs, When pulsar's official website successfully builds 2.6.2 docs, we should move the default version of docs to 2.6.2.
yahoo/pulsar,massakam/pulsar,merlimat/pulsar,yahoo/pulsar,massakam/pulsar,yahoo/pulsar,massakam/pulsar,merlimat/pulsar,massakam/pulsar,merlimat/pulsar,yahoo/pulsar,merlimat/pulsar,massakam/pulsar,yahoo/pulsar,merlimat/pulsar,merlimat/pulsar,massakam/pulsar,yahoo/pulsar