Add language around targeting dev branch (#457)

Author: thekaveman

.github/pull_request_template.md

@@ -1,23 +1,29 @@
-### Explain pull request
+# MDS Pull Request
+
+Thank you for your contribution!
+
+*For most Pull Requests, the target branch should be [**`dev`**](https://github.com/openmobilityfoundation/mobility-data-specification/tree/dev). Please ensure you are targeting **`dev`** to avoid complications and help make the Review process as smooth as possible.*
+
+## Explain pull request
 
 Please provide a clear and concise reason for this pull request and the impact of the change
 
-### Is this a breaking change
+## Is this a breaking change
 
-A breaking change would require consumers or implementors of the API to modify their code for it to continue to function (ex: renaming of a required field or the change in data type of an existing field). A non-breaking change would allow existing code to continue to function (ex: addition of an optional field or the creation of a new optional endpoint). 
+A breaking change would require consumers or implementors of the API to modify their code for it to continue to function (ex: renaming of a required field or the change in data type of an existing field). A non-breaking change would allow existing code to continue to function (ex: addition of an optional field or the creation of a new optional endpoint).
 
- * Yes, breaking
- * No, not breaking
- * I'm not sure
+* Yes, breaking
+* No, not breaking
+* I'm not sure
 
-### Impacted Spec
+## Impacted Spec
 
 Which spec(s) will this pull request impact?
 
- * `agency`
- * `policy`
- * `provider`
+* `agency`
+* `policy`
+* `provider`
 
-### Additional context
+## Additional context
 
 Add any other context or screenshots about the feature request here.