Refer to official libcouchbase installation instructions

Change-Id: I3ccbc69114c6b8ffc9bc8c2c6baf9e4312bac8d6
Reviewed-on: http://review.couchbase.org/43856
Reviewed-by: Sergey Avseyev <sergey.avseyev@gmail.com>
Tested-by: Sergey Avseyev <sergey.avseyev@gmail.com>