ISSUE_TEMPLATE: revert one-sentence-per-line for package_request

We tried, but GitHub's markdown renderer will render these newlines
there, so going back to "real" paragraphs.

Also fixed the emphasis slightly, since "via Issues" is not bold, "via a
Pull Request" is also made not bold for consistency. Puts the focus more
on the "contribute" link as well.

.github/ISSUE_TEMPLATE/10_package_request.yml

···
           </a>
         </p>
 
-        Thank you for your interest in packaging new software in Nixpkgs.
-        Unfortunately, to mitigate the unsustainable growth of unmaintained packages, **Nixpkgs is no longer accepting package requests** via Issues.
+        Thank you for your interest in packaging new software in Nixpkgs. Unfortunately, to mitigate the unsustainable growth of unmaintained packages, **Nixpkgs is no longer accepting package requests** via Issues.
 
-        As a [volunteer community][community], we are always open to new contributors.
-        If you wish to see this package in Nixpkgs, **we encourage you to [contribute] it yourself, via a Pull Request**.
-        Anyone can [become a package maintainer][maintainers]!
-        You can find language-specific packaging information in the [Nixpkgs Manual][nixpkgs].
-        Should you need any help, please reach out to the community on [Matrix] or [Discourse].
+        As a [volunteer community][community], we are always open to new contributors. If you wish to see this package in Nixpkgs, **we encourage you to [contribute] it yourself**, via a Pull Request. Anyone can [become a package maintainer][maintainers]! You can find language-specific packaging information in the [Nixpkgs Manual][nixpkgs]. Should you need any help, please reach out to the community on [Matrix] or [Discourse].
 
         [community]: https://nixos.org/community
         [contribute]: https://github.com/NixOS/nixpkgs/blob/master/pkgs/README.md#quick-start-to-adding-a-package