[documentation] Issue 2386: release notes link of old versions broken (#2388)
[documentation] Issue 2386: release notes link of old versions broken (#2388)

### Motivation

Fixes #2386.

Release notes links of old versions are broken due to an additional "/".

 ### Changes

Remove the extra "/"
ArvinDevel/incubator-pulsar,massakam/pulsar,jai1/pulsar,ArvinDevel/incubator-pulsar,yahoo/pulsar,yahoo/pulsar,jai1/pulsar,ArvinDevel/incubator-pulsar,ArvinDevel/incubator-pulsar,nkurihar/pulsar,ArvinDevel/incubator-pulsar,merlimat/pulsar,jai1/pulsar,nkurihar/pulsar,jai1/pulsar,nkurihar/pulsar,massakam/pulsar,nkurihar/pulsar,nkurihar/pulsar,ArvinDevel/incubator-pulsar,nkurihar/pulsar,yahoo/pulsar,ArvinDevel/incubator-pulsar,jai1/pulsar,nkurihar/pulsar,merlimat/pulsar,yahoo/pulsar,yahoo/pulsar,massakam/pulsar,jai1/pulsar,massakam/pulsar,merlimat/pulsar,merlimat/pulsar,merlimat/pulsar,jai1/pulsar,ArvinDevel/incubator-pulsar,jai1/pulsar,yahoo/pulsar,jai1/pulsar,nkurihar/pulsar,massakam/pulsar,massakam/pulsar,merlimat/pulsar,nkurihar/pulsar