Add GitHub issue templates (#8934)

* Add GitHub issue templates

* Fix Stack Overflow wording

Co-Authored-By: Sijawusz Pur Rahnama <sija@sija.pl>

* Fix typo

Co-Authored-By: Sijawusz Pur Rahnama <sija@sija.pl>

* Better phrasing

Co-Authored-By: Sijawusz Pur Rahnama <sija@sija.pl>

* Change discussion to question

* Improve template chooser sentences

* Remove duplication

* Put back status:discussion

Co-authored-by: Sijawusz Pur Rahnama <sija@sija.pl>

ISSUE_TEMPLATE.md → .github/ISSUE_TEMPLATE/bug-report.md

@@ -1,12 +1,14 @@
-# Submitting questions
+---
+name: "\U0001F41B Bug Report"
+about: I want to report a bug.
+labels: kind:bug
+---
 
-If you have a question like "how do I do X?", this is not the right place for asking it. Please ask on the [Crystal Forum](https://forum.crystal-lang.org), on our combined [Gitter](https://gitter.im/crystal-lang/crystal)/[IRC](http://webchat.freenode.net/?channels=#crystal-lang) or on [StackOverflow](http://stackoverflow.com/questions/tagged/crystal-lang).
-
-# Submitting bugs
+## Bug Report
 
 Make sure to review these points before submitting issues - thank you!
 
-- Make sure a similar issue doesn't exist yet: use the search box
+- Make sure a similar issue does not exist yet: use the search box, search engine and look at [Stack Overflow](https://stackoverflow.com/questions/tagged/crystal-lang).
 - **Include reproducible code**: we should be able to paste it into an editor, compile and run it and get the same error as you. Otherwise it's impossible for us to reproduce the bug.
 - Don't **only** use `play.crystal-lang.org` or `carc.in`: code might be lost and the issue will remain incomplete. Write code in the issue itself.
 - Reduce code, if possible, to the minimum size that reproduces the bug.

.github/ISSUE_TEMPLATE/config.yml

@@ -0,0 +1,8 @@
+blank_issues_enabled: false
+contact_links:
+  - name: "\U00002753 Crystal Community Forum"
+    url: https://forum.crystal-lang.org/c/help-support
+    about: Questions about installing, using Crystal and any related issues.
+  - name: "\U0001F4AC Crystal Community Chat"
+    url: https://gitter.im/crystal-lang/crystal
+    about: "Get in touch with the community, ask for help and talk about Crystal. (IRC: #crystal-lang on freenode)"

.github/ISSUE_TEMPLATE/discussion.md

@@ -0,0 +1,12 @@
+---
+name: "\U0001F914 Language Improvement Discussion"
+about: I want to start a new discussion about improving the language.
+labels: status:discussion
+---
+
+## Discussion
+
+- What aspect of the language would you like to see improved?
+- What are the reasons?
+- Include practical examples to illustrate your points.
+- Optionally add one (or more) proposals to improve the current situation.

.github/ISSUE_TEMPLATE/feature-request.md

@@ -0,0 +1,12 @@
+---
+name: "\U0001F680 Feature Request"
+about: I want to propose a new language feature.
+labels: kind:feature
+---
+
+## Feature Request
+
+- Is your feature request related to a problem? Please describe clearly and concisely what is it.
+- Describe the feature you would like, optionally illustrated by examples, and how it will solve the above problem.
+- Describe considered alternative solutions, and the reasons why you have not proposed them as a solution here.
+- Does it break backward compatibility, if yes then what's the migration path?