Update README.md PR instructions.
diff --git a/README.md b/README.md
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## Submitting Pull Requests
-Pull requests are welcome. However, please create them with a request
+Pull requests are welcome. Some guidelines:
+
+* Please do not use functions or facilities that are not standard (e.g.,
+`strlcpy()`, `fpurge()`).
+
+* Please run the test suite and make sure that your changes pass before
+posting the pull request. To do so:
+
+ 1. Save the previous version of `awk` somewhere in your path. Call it `nawk` (for example).
+ 1. Run `oldawk=nawk make check > check.out 2>&1`.
+ 1. Search for `BAD` or `error` in the result. In general, look over it manually to make sure there are no errors.
+
+* Please create the pull request with a request
to merge into the `staging` branch instead of into the `master` branch.
This allows us to do testing, and to make any additional edits or changes
after the merge but before merging to `master`.
