Add documentation, Move to accessibility folder, Add config

Author: Adrián Bolonio

config/accessibility.yml

@@ -3,4 +3,7 @@ require:
 
 GitHub/Accessibility/ImageHasAlt:
   Enabled: true
-  StyleGuide: https://github.com/github/rubocop-github/blob/master/guides/image-has-alt.md
+  StyleGuide: https://github.com/github/rubocop-github/blob/master/guides/image-has-alt.md
+GitHub/Accessibility/NoRedundantImageAlt:
+  Enabled: true
+  StyleGuide: https://github.com/github/rubocop-github/blob/master/guides/no-redundant-image-alt.md

guides/no-redundant-image-alt.md

@@ -0,0 +1,24 @@
+# GitHub/Accessibility/NoRedundantImageAlt
+
+## Rule Details
+
+Alt prop should not contain `image` or `picture` as screen readers already announce the element as an image
+
+## Resources
+
+- [W3C WAI Images Tutorial](https://www.w3.org/WAI/tutorials/images/)
+- [Primer: Alternative text for images](https://primer.style/design/accessibility/alternative-text-for-images)
+
+## Examples
+### **Incorrect** code for this rule 👎
+
+```erb
+<%= image_tag "cat.gif", size: "12x12", alt: "Picture of a cat" %>
+```
+
+### **Correct** code for this rule  👍
+
+```erb
+<!-- good -->
+<%= image_tag "cat.gif", size: "12x12", alt: "A black cat" %>
+```

lib/rubocop/cop/github/rails_no_redundant_image_alt.rb renamed to lib/rubocop/cop/github/accessibility/no_redundant_image_alt.rb

@@ -2,7 +2,7 @@
 
 require_relative "./cop_test"
 require "minitest/autorun"
-require "rubocop/cop/github/rails_no_redundant_image_alt"
+require "rubocop/cop/github/accessibility/no_redundant_image_alt"
 
 class NoRedundantImageAlt < CopTest
   def cop_class