add a CONTRIBUTING.md file

add a CONTRIBUTING.md file, copied verbatim from the "Pull Requests" section in README.md

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644 (file)
index 0000000..918dd5e
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,3 @@
+Since this repo includes a large and diverse number of programming languages, frameworks, editors, and ecosystems, it's *very helpful* if you can provide a link to information supporting your pull request. Up-to-date, canonical documentation that mentions the files to be ignored is best.
+
+This ensures we can efficiently go through pull requests and keep quality high.