Add an initial pull-request template

.github/pull_request_template.md

@@ -0,0 +1,13 @@
+## Thank you for sending in a pull request, here's some tips to get started!
+
+(Please delete all these tips and replace with your text)
+
+- Before starting on some new big chunk of code, it it is optional but highly recommended to open an issue first
+  to say "hey, I think this idea X should be implemented and I'm starting work on it. My general plan is Y, any feedback
+  is appreciated." This will allow other devs to potentially save you time by not accidentially duplicating work etc...
+- Please do not check in files that don't have real changes
+- Please do not reformat lines that you didn't have to change the code on
+- We recommend using the [Visual Studio Code](https://platformio.org/install/ide?install=vscode) editor,
+  because automatically follows our indentation rules and it's auto reformatting will not cause spurious changes to lines.
+- If your PR fixes a bug, mention "fixes #bugnum" somewhere in your pull request description.
+- If your other co-developers have comments on your PR please tweak as needed.