Fix link to opensearch-ruby

[juergen-walter]

It just fixes a broken pointer in the documentation

(check all that apply)

• tests added
• tests passing
• README updated (if needed)
• README Table of Contents updated (if needed)
• History.md and version in gemspec are untouched
• backward compatible

[cosmo0920]

Looks reasonable but fluent org repos request to use Signed-off in the commits.
Could you add this signature with git commit -s --amend and git push origin patch-1?

[juergen-walter]

Sorry, I did not align to the guidelines in the first place. Could have assumed it, did not check due to minor issue and time pressure for other topics. Just provided the fix via the github web ui quickly.

Thanks for sharing even the commands. Must be git push origin patch-1 -f ;-)