add issue templates (0xPolygonHermez#1893)

.github/ISSUE_TEMPLATE/bug.md

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+---
+name: Report a bug
+about: Something with Polygon zkEVM is not working as expected
+title: ''
+labels: 'type:bug'
+assignees: ''
+---
+
+#### System information
+
+zkEVM Node version: `v0.0.X-RCXX`
+OS & Version: `Windows/Linux/OSX`
+Commit hash : (if `develop`)
+Network: `Mainnet/Testnet`
+
+#### Expected behaviour
+
+
+#### Actual behaviour
+
+
+#### Steps to reproduce the behaviour
+
+
+#### Backtrace
+
+````
+[backtrace]
+````
+
+When submitting logs: please submit them as text and not screenshots.

.github/ISSUE_TEMPLATE/feature.md

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+---
+name: Request a feature
+about: Report a missing feature - e.g. as a step before submitting a PR
+title: ''
+labels: 'type:feature'
+assignees: ''
+---
+
+# Rationale
+
+Why should this feature exist?
+What are the use-cases?
+
+# Implementation
+
+Do you have ideas regarding the implementation of this feature?
+Are you willing to implement this feature?

.github/ISSUE_TEMPLATE/question.md

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+---
+name: Ask a question
+about: Something is unclear
+title: ''
+labels: 'type:question'
+assignees: ''
+---
+
+This should only be used in very rare cases e.g. if you are not 100% sure if something is a bug or asking a question that leads to improving the documentation.