chore(docs): Added contribution templates, SECURITY policy

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,47 @@
+---
+name: Bug report
+about: Report a bug encountered while using ERPNext
+labels: bug
+---
+
+<!--
+Welcome to ERPNext issue tracker! Before creating an issue, please heed the following:
+
+1. This tracker should only be used to report bugs and request features / enhancements to ERPNext
+    - For questions and general support, checkout the manual https://erpnext.com/docs/user/manual/en or use https://discuss.erpnext.com
+    - For documentation issues, refer to https://github.com/frappe/erpnext_com
+2. Use the search function before creating a new issue. Duplicates will be closed and directed to
+   the original discussion.
+3. When making a bug report, make sure you provide all required information. The easier it is for
+   maintainers to reproduce, the faster it'll be fixed.
+4. If you think you know what the reason for the bug is, share it with us. Maybe put in a PR 😉
+-->
+
+## Description of the issue
+
+## Context information (for bug reports)
+
+**Output of `bench version`**
+```
+(paste here)
+```
+
+## Steps to reproduce the issue
+
+1.
+2.
+3.
+
+### Observed result
+
+### Expected result
+
+### Stacktrace / full error message
+
+```
+(paste here)
+```
+
+## Additional information
+
+OS version / distribution, `ERPNext` install method, etc.