Add PR templates

Author: bencroker

.github/PULL_REQUEST_TEMPLATE/change-behavior.md

@@ -0,0 +1,5 @@
+### Change in Behavior
+
+Please provide appropriate justification for this change in behavior, clearly describing the problem, solution, and alternatives considered.
+
+Before contributing, please read the [contribution guidelines](https://github.com/starfederation/datastar/blob/develop/CONTRIBUTING.md).

.github/PULL_REQUEST_TEMPLATE/new-behavior.md

@@ -0,0 +1,5 @@
+### New Behavior
+
+Please provide appropriate justification for this new behavior, clearly describing the problem, solution, and alternatives considered.
+
+Before contributing, please read the [contribution guidelines](https://github.com/starfederation/datastar/blob/develop/CONTRIBUTING.md).

CONTRIBUTING.md

@@ -4,7 +4,7 @@ Thanks for thinking about contributing to Datastar 🚀
 
 ## Before You Contribute
 
-Before you contribute, please consider that Datastar is developed and maintained by a a small team of core contributors in a private repo. The source code for each version is made available in the public repo.
+Before you contribute, please consider that Datastar is developed and maintained by a a small team of core contributors in a _private_ repo. The source code for each version is made available in the public repo.
 
 ## Bug Reports
 
@@ -16,7 +16,7 @@ Before requesting a new feature, please consider that Datastar is a lightweight
 
 ## Pull Requests
 
-Always open an issue to discuss your idea _before_ submitting a pull request. Pull requests must be made to the `develop` branch, have a descriptive title and clearly describe the problem and solution. If the pull request adds or changes behavior, documentation and examples should be updated accordingly.
+Always open an issue to discuss your idea _before_ submitting a pull request. Pull requests must be made to the `develop` branch, have a descriptive title and clearly describe the problem and solution. If the pull request adds or changes behavior, appropriate justification _must_ be provided, and documentation and examples should be updated accordingly.
 
 ## SDKs