feat: Add article for Elixir Keyword Lists (#36141)

guide/english/elixir/keyword-lists/index.md

@@ -3,11 +3,22 @@ title: Keyword Lists
 ---
 ## Keyword Lists
 
-This is a stub. <a href='https://github.com/freecodecamp/guides/tree/master/src/pages/elixir/keyword-lists/index.md' target='_blank' rel='nofollow'>Help our community expand it</a>.
+Keyword Lists are used for storing the key-value pairs as tuples.
 
-<a href='https://github.com/freecodecamp/guides/blob/master/README.md' target='_blank' rel='nofollow'>This quick style guide will help ensure your pull request gets accepted</a>.
+```shell
+iex(1)> iex(3)> kw_list = [{:key1, "Val1"}, {:key2, "Val2"}, {:key1, "It is OK to repeat key1"}]
+[key1: "Val1", key2: "Val2", key1: "It is OK to repeat key1"]
+```
+curly braces can be omitted as seen in the `iex` response on the second line.
 
-<!-- The article goes here, in GitHub-flavored Markdown. Feel free to add YouTube videos, images, and CodePen/JSBin embeds  -->
+In Keyword Lists, the Keys :
+
+- Must be atoms
+- Can be repeated
+- Are ordered as specified by the developer.
+
+Keyword lists are default mechanism for passing options to functions in Elixir.
 
 #### More Information:
-<!-- Please add any articles you think might be helpful to read before writing the article -->
+ * [Elixir Documentation](https://elixir-lang.org/getting-started/keywords-and-maps.html#keyword-lists)
+ * [Keyword HexDocs](https://hexdocs.pm/elixir/Keyword.html)