[Chore] Update github issues templates (#2021)

* Removes Design Task template
* Removes Simple Task template
* Renames Issue template into Bug and adds more details and structure
* Updates markup of the Request a feature template
* Updates the link to the discord server

Author: carterqw2

.github/ISSUE_TEMPLATE/bug.md

@@ -0,0 +1,43 @@
+---
+name: Report a bug
+about: When something is not working as expected
+title: ''
+labels: triage, type:bug
+assignees: ''
+
+---
+
+## Expected Behavior
+
+_Explain the expected behavior._
+
+## Actual Behavior
+
+_Explain what the current behavior is._
+
+## Steps to reproduce the behavior
+
+1. Specific steps to reproduce the bug.
+
+## Backtrace
+
+```
+  error output with backtrace
+```
+
+## System Information
+
+Client version:
+
+```bash
+./geth version
+```
+
+geth command with flags:
+
+```bash
+./geth %flags%
+
+```
+
+Chain/Network: `Alfajores/Baklava/Mainnet`

.github/ISSUE_TEMPLATE/chore.md

@@ -6,12 +6,12 @@ labels: triage, 'type:feature'
 assignees: ''
 ---
 
-# Rationale
+## Rationale
 
 Why should this feature exist?
 What are the use-cases?
 
-# Implementation
+## Implementation
 
 Do you have ideas regarding the implementation of this feature?
 Are you willing to implement this feature?

.github/ISSUE_TEMPLATE/design_task.md

@@ -6,4 +6,4 @@ labels: triage, 'type:docs'
 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. For general questions please use [discord](https://discord.gg/nthXNEv) or the Ethereum stack exchange at https://ethereum.stackexchange.com.
+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. For general questions please use [Celo discord](https://discord.gg/celo).