Add a workflow to check documentations (#1151)

* Add a workflow to check documentations

* Fix markdown issues

* Install Ruby 2.7

* Finally, handle and fix GitHub templates

* Minor improvement in the feature request template

* Verbose mode to be sure all files are checked

.github/ISSUE_TEMPLATE/bug_report.md

@@ -7,34 +7,44 @@ assignees: ''
 
 ---
 
-**Checklist**
+## Checklist
 
 - [ ] I've searched for similar issues.
 - [ ] I'm using the latest version of HTTPie.
 
 ---
 
-**What are the steps to reproduce the problem?**
+## Minimal reproduction code and steps
 
 1.
 2.
 3.
 
+---
 
-**What is the expected result?**
+## Expected result
 
+…
 
-**What happens instead?**
+---
 
+## Current result
 
-**Debug output**
+…
+
+---
+
+## Debug output
 
 Please re-run the command with `--debug`, then copy the entire command & output and paste both below:
 
-```
+```bash
 $ http --debug <COMPLETE ARGUMENT LIST THAT TRIGGERS THE ERROR>
 <COMPLETE OUTPUT>
 ```
 
+---
 
-**Provide any additional information, screenshots, or code examples below:**
+## Additional information, screenshots, or code examples
+
+…

.github/ISSUE_TEMPLATE/feature_request.md

@@ -6,19 +6,25 @@ labels: "new, enhancement"
 assignees: ''
 
 ---
-**Checklist**
+
+## Checklist
 
 - [ ] I've searched for similar feature requests.
 
 ---
 
-**What enhancement would you like to see?**
+## Enhancement request
 
+…
 
-**What problem does it solve?**
+---
 
-E.g. “I'm always frustrated when [...]”, “I’m trying to do […] so that […]”.
+## Problem it solves
 
+E.g. “I'm always frustrated when […]”, “I’m trying to do […] so that […]”.
 
-**Provide any additional information, screenshots, or code examples below:**
+---
 
+## Additional information, screenshots, or code examples
+
+…

.github/workflows/documentations.yml

@@ -0,0 +1,21 @@
+name: Check documentations
+
+on:
+  pull_request:
+    paths:
+      - "*.md"
+      - "**/*.md"
+
+jobs:
+  doc:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - name: Setup Ruby
+        uses: ruby/setup-ruby@v1
+        with:
+          ruby-version: 2.7
+      - name: Install the linter
+        run: sudo gem install mdl
+      - name: Check files
+        run: make doc-check