Create PULL_REQUEST_TEMPLATE.md (espressif#5439)

Adding first version of PULL_REQUEST_TEMPLATE.md. The purpose of this template is to improve and simplify writing more accurate Release Notes.

Author: VojtechBartoska

.github/PULL_REQUEST_TEMPLATE.md

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+----------------------------------------------------------------------------------------------------------------------------------------------------
+This entire section can be deleted if all items are checked.
+
+*By completing this PR sufficiently, you help us to improve the quality of Release Notes*
+
+### Checklist
+
+1. [ ] Please provide specific title of the PR describing the change, including the component name (eg."Update of Documentation link on Readme.md")
+2. [ ] Please provide related links (eg. Issue, other Project, submodule PR..)
+----------------------------------------------------------------------------------------------------------------------------------------------------
+
+## Summary
+Please describe your proposed PR and what it contains.
+
+## Impact
+Please describe impact of your PR and it's function.