doc: update CONTRIBUTING.md file.

CONTRIBUTING.md

@@ -1,22 +1,22 @@
-# Contributing to ief
-
-- [Contributing to ief](#contributing-to-ief)
-  - [Code Contributions](#code-contributions)
-      - [Step 1: Clone](#step-1-clone)
-      - [Step 2: Branch](#step-2-branch)
-      - [Step 3: Commit](#step-3-commit)
-      - [Step 4: Sync](#step-4-sync)
-      - [Step 5: Push](#step-5-push)
-      - [Step 6: Pull Request](#step-6-pull-request)
-  - [Commit message guidelines](#commit-message-guidelines)
-  - [Coding guidelines](#coding-guidelines)
-      - [Code structuring patterns](#code-structuring-patterns)
-          - [Object Oriented Programming](#object-oriented-programming)
-          - [Functional Programming](#functional-programming)
-      - [Naming patterns](#naming-patterns)
-      - [Documentation](#documentation)
-      - [Writing tests](#writing-tests)
-
+# Contributing to ief <!-- omit from toc -->
+
+## Table of Contents <!-- omit from toc -->
+
+- [Code Contributions](#code-contributions)
+    - [Step 1: Clone](#step-1-clone)
+    - [Step 2: Branch](#step-2-branch)
+    - [Step 3: Commit](#step-3-commit)
+    - [Step 4: Sync](#step-4-sync)
+    - [Step 5: Push](#step-5-push)
+    - [Step 6: Pull Request](#step-6-pull-request)
+- [Commit message guidelines](#commit-message-guidelines)
+- [Coding guidelines](#coding-guidelines)
+    - [Code structuring patterns](#code-structuring-patterns)
+        - [Object Oriented Programming](#object-oriented-programming)
+        - [Functional Programming](#functional-programming)
+    - [Naming patterns](#naming-patterns)
+    - [Documentation](#documentation)
+    - [Writing tests](#writing-tests)
 
 ## Code Contributions