Helping contributors. (#1289)

.github/pull_request_template.md

@@ -0,0 +1,8 @@
+
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+Our tests check whether you have introduced trailing white space. If such a test fails, please check the "artifacts button" above, which if you click it gives a link to a downloadable file to help you identify the issue. You can also run scripts/remove_trailing_whitespace.sh locally if you have a bash shell and the sed command available on your system.
+
+If you plan to contribute to simdjson, please read our
+
+CONTRIBUTING guide: https://github.com/simdjson/simdjson/blob/master/CONTRIBUTING.md and our
+HACKING guide: https://github.com/simdjson/simdjson/blob/master/HACKING.md

CONTRIBUTING.md

@@ -42,6 +42,7 @@ We have few hard rules, but we have some:
 - Calls to `abort()` are forbidden in the core library. This follows from the [Writing R Extensions](https://cran.r-project.org/doc/manuals/R-exts.html) manual which states that "Under no circumstances should your compiled code ever call abort or exit".
 - All source code files (.h, .cpp) must be ASCII.
 - All C macros introduced in public headers need to be prefixed with either `SIMDJSON_` or `simdjson_`.
+- We avoid trailing white space characters within lines. That is, your lines of code should not terminate with unnecessary spaces. Generally, please avoid making unnecessary changes to white-space characters when contributing code.
 
 Tools, tests and benchmarks are not held to these same strict rules.