Mention the Slack channel

Author: cjbj

INSTALL.md

@@ -1659,8 +1659,8 @@ If `require('oracledb')` fails:
   did not self-register*?  You must rebuild node-oracledb when you
   upgrade Node.js.
 
-Questions and issues can be posted as [GitHub Issues][10].
-
+Issues and questions about node-oracledb can be posted on [GitHub][10] or
+[Slack][48] ([link to join Slack][49]).
 
 
 [1]: http://oracle.github.io/node-oracledb/
@@ -1709,3 +1709,5 @@ Questions and issues can be posted as [GitHub Issues][10].
 [45]: https://www.youtube.com/watch?v=WDJacg0NuLo
 [46]: http://yum.oracle.com/oracle-linux-nodejs.html
 [47]: https://oracle.github.io/node-oracledb/doc/api.html#migrate
+[48]: https://node-oracledb.slack.com/
+[49]: https://join.slack.com/t/node-oracledb/shared_invite/enQtNDI4NTUyNjMzMDA5LWRiZWRkZjQ3NjBhNDUwOGJlNDFiZWJhZTIzYTJkMWQ5N2UwNTg5NzNmNmY1YmZjZGYxNmRhOTkyOTlhMmViNjY