adjust redirect for grpc link

[christinaausley]

Description

Closes https://github.com/camunda/doc-hospital/issues/14.

When should this change go live?

• This change is not yet live and should not be merged until {ADD_DATE} (apply hold label or convert to draft PR)?
• There is no urgency with this change.
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• This functionality is already available but undocumented.
• This is a bug fix or security concern.

PR Checklist

• I have added changes to the relevant /versioned_docs directory, or they are not for an already released version.
• I have added changes to the main /docs directory (aka /next/), or they are not for future versions.
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[akeller]

This looks like a very old redirect, before we added a trailing slash.

@pepopowitz would it make sense to audit the other rules without a trailing slash too?

[pepopowitz]

We definitely could, but I personally feel like that's a task that will sit on our board due to low priority and we'll never get to it. If you're feeling ambitious though, go for it!