Merge #16806: doc: Add issue templates for bug and feature request

fabca77 doc: Add issue templates for bug and feature request (MarcoFalke)

Pull request description:

  Fixes #16627

  Can be tested via https://github.com/MarcoFalke/bitcoin/issues

ACKs for top commit:
  jb55:
    ACK fabca77
  fanquake:
    ACK fabca77

Tree-SHA512: 1ebe58f9c0110a9332adf1d80001cd9ed6fe60208e387c93b8564dc66821f753e34b23cb6f4cae45168024862ee884913976e132820b7a4759fa6391b0d1127c

Author: MarcoFalke

.github/ISSUE_TEMPLATE.md

@@ -17,7 +17,7 @@ If the node is "stuck" during sync or giving "block checksum mismatch" errors, p
 
 <!-- What type of machine are you observing the error on (OS/CPU and disk type)? -->
 
-<!-- For the GUI-related issue on Linux provide names and versions of a distro, a desktop environment and a graphical shell (if relevant). -->
+<!-- GUI-related issue? What is your operating system and its version? If Linux, what is your desktop environment and graphical shell? -->
 
 <!-- Any extra information that might be useful in the debugging process. -->
 <!--- This is normally the contents of a `debug.log` or `config.log` file. Raw text or a link to a pastebin type site are preferred. -->

.github/ISSUE_TEMPLATE/bug_report.md

@@ -0,0 +1,41 @@
+---
+name: Bug report
+about: Create a report to help us improve
+title: ''
+labels: Bug
+assignees: ''
+
+---
+
+<!-- This issue tracker is only for technical issues related to Bitcoin Core.
+
+General bitcoin questions and/or support requests are best directed to the Bitcoin StackExchange at https://bitcoin.stackexchange.com.
+
+For reporting security issues, please read instructions at https://bitcoincore.org/en/contact/.
+
+If the node is "stuck" during sync or giving "block checksum mismatch" errors, please ensure your hardware is stable by running memtest and observe CPU temperature with a load-test tool such as linpack before creating an issue! -->
+
+<!-- Describe the issue -->
+
+**Expected behavior**
+
+<!--- What behavior did you expect? -->
+
+**Actual behavior**
+
+<!--- What was the actual behavior (provide screenshots if the issue is GUI-related)? -->
+
+**To reproduce**
+
+<!--- How reliably can you reproduce the issue, what are the steps to do so? -->
+
+**System information**
+
+<!-- What version of Bitcoin Core are you using, where did you get it (website, self-compiled, etc)? -->
+
+<!-- What type of machine are you observing the error on (OS/CPU and disk type)? -->
+
+<!-- GUI-related issue? What is your operating system and its version? If Linux, what is your desktop environment and graphical shell? -->
+
+<!-- Any extra information that might be useful in the debugging process. -->
+<!--- This is normally the contents of a `debug.log` or `config.log` file. Raw text or a link to a pastebin type site are preferred. -->

.github/ISSUE_TEMPLATE/feature_request.md

@@ -0,0 +1,20 @@
+---
+name: Feature request
+about: Suggest an idea for this project
+title: ''
+labels: Feature
+assignees: ''
+
+---
+
+**Is your feature request related to a problem? Please describe.**
+<!-- A clear and concise description of what the problem is. Ex. I'm always frustrated when [...] -->
+
+**Describe the solution you'd like**
+<!-- A clear and concise description of what you want to happen. -->
+
+**Describe alternatives you've considered**
+<!-- A clear and concise description of any alternative solutions or features you've considered. -->
+
+**Additional context**
+<!-- Add any other context or screenshots about the feature request here. -->