(#92) Docs: update the maintainer guide

MAINTAINERSHIP.md

@@ -27,9 +27,11 @@ To update the key:
 
 1. Sign in onto nuget.org.
 2. Go to the [API keys][nuget.api-keys] section.
-3. Create a new key with permission to **Push new packages and package versions** and only allowed to publish **tdlib.native** package.
+3. Create a new key with permission to **Push only new package versions** with the glob pattern of `github-actions.tdlib.native`.
 
    Alternately, if you have such key already and want to regenerate it, press the **Regenerate** button in its page section.
+
+   If you are adding a new package, then use the **Push new packages and package versions** permission, but limit the key lifetime to the minimum possible date range — you will refresh it again using the limited set of permissions next time.
 4. Paste the generated API keys to the [action secrets][github.secrets] section on GitHub settings (update the `NUGET_KEY` secret).
 
 [docs.unlist]: https://docs.microsoft.com/en-us/nuget/nuget-org/policies/deleting-packages#unlisting-a-package