misc: added templates for issue and pull request.

Signed-off-by: Yichun Zhang (agentzh) <agentzh@gmail.com>

.github/ISSUE_TEMPLATE.md

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+This place is for bug reports and development discussions only. For general questions and
+discussions, please join the openresty-en mailing list instead: https://groups.google.com/group/openresty-en.
+If you want to use Chinese, please join the openresty (Chinese) mailing list instead: https://groups.google.com/group/openresty.
+Do not use Chinese in this place.
+
+Before you open a new issue, please search the internet and make sure it is not duplicate.
+
+Ensure you have provided the following details while reporting a problem:
+
+- [ ] The exact version of the related software, including but not limited to the OpenResty version
+(if any), the NGINX core version, the `ngx_lua` module version(via `openresty -V` or `nginx -V`),
+and your operating system version(via `uname -a`).
+- [ ] **A minimal and standalone test case** that others can easily run on their side and
+reproduce the issue you are seeing.
+- [ ] Do not simply say "something is broken" or "something does not work". Always provide
+as much details as possible. Always describe **the symptoms and your expected results**.
+
+You can (temporarily) enable the nginx debugging logs to see the internal workings
+of NGINX in your nginx''s `error.log` file. See http://nginx.org/en/docs/debugging_log.html
+The same instructions apply equally well to OpenResty.
+
+If you are seeing crashes, please provide the full backtrace for the crash. See
+https://www.nginx.com/resources/wiki/start/topics/tutorials/debugging/#core-dump
+for more details.
+
+Thanks for your cooperation.

.github/PULL_REQUEST_TEMPLATE.md

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+I hereby granted the copyright of the changes in this pull request
+to the authors of this openresty project.