chore: update PR template (#111)

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.github/PULL_REQUEST_TEMPLATE.md

@@ -1 +1,7 @@
-Fixes #<issue_number_goes_here> (it's a good idea to open an issue first for context and/or discussion)
+Thank you for opening a Pull Request! Before submitting your PR, there are a few things you can do to make sure it goes smoothly:
+- [ ] Make sure to open an issue as a [bug/issue](https://github.com/googleapis/java-asset/issues/new/choose) before writing your code!  That way we can discuss the change, evaluate designs, and agree on the general idea
+- [ ] Ensure the tests and linter pass
+- [ ] Code coverage does not decrease (if any source code was changed)
+- [ ] Appropriate docs were updated (if necessary)
+
+Fixes #<issue_number_goes_here> ☕️

synth.metadata

@@ -1,5 +1,5 @@
 {
-  "updateTime": "2020-03-13T19:28:49.240096Z",
+  "updateTime": "2020-03-16T16:37:41.034665Z",
   "sources": [
     {
       "generator": {