docs: add template for documentation

.github/ISSUE_TEMPLATE/documentation_template.md

+---
+name: Documentation Template
+about: Use this template to propose changes and updates to documentation
+title: ""
+labels: documentation
+assignees: ""
+---
+
+**Report Type**
+
+- [ ] Missing documentation
+- [ ] Fix current documentation (errors)
+
+**What is the URL of the documentation (if applicable)?**
+- Example:https://hub.datree.io/schema-validation
+ 
+**What can be improved?**  
+A clear and concise description of what can be improved.
+Examples:  
+- "I don't understand where the ${XYZ} variable is set."
+- "There seems to be a step missing between 'X' and 'Z'.   I don't know how to get to 'Z'."
+- "When I run `command sub-command ...`  I get the following error:"
+- "I don't know what is meant by 'gerble barb gazoink` in the instructions".
+
+**Suggested Solution**  
+Detail proposed changes to update the documentation if you have any.
+
+**Acceptance Criteria**  
+Provide requirements to test that the documentation is correct