[ANNOUNCE] EOL HBase 1.3.x release line

[Duo Zhang]

HBase 1.3.6 will be the last release of the 1.3.x release line.

Users are encouraged to upgrade to the 1.4.x release line, and then to 2.x
release line.

Thank you for trusting and choosing the 1.3.x release line.

Best,
The HBase Dev Team