docs: Be more precise when pushing tags on release. (#6483)

Signed-off-by: Bartek Plotka <bwplotka@gmail.com>

RELEASE.md

@@ -77,7 +77,7 @@ You can do the tagging on the commandline:
 ```bash
 $ tag=$(< VERSION)
 $ git tag -s "v${tag}" -m "v${tag}"
-$ git push --tags
+$ git push origin "v${tag}"
 ```
 
 Signing a tag with a GPG key is appreciated, but in case you can't add a GPG key to your Github account using the following [procedure](https://help.github.com/articles/generating-a-gpg-key/), you can replace the `-s` flag by `-a` flag of the `git tag` command to only annotate the tag without signing.