Add README.

Author: ilopX

patterns/iterator/github_commit/README.md

@@ -0,0 +1,44 @@
+# Template Method Pattern
+Iterator is a behavioral design pattern that lets you traverse elements of a collection without 
+exposing its underlying representation (list, stack, tree, etc.).
+
+Tutorial: [here](https://refactoring.guru/design-patterns/iterator).
+
+## Diagram:
+![image](https://user-images.githubusercontent.com/8049534/183165928-7274e761-09e3-48ce-b9c1-41d552fa1f1a.png)
+
+
+### Client code:
+```dart
+void main() async {
+  final GitHubRepo gitHubRepo = await GitHubLoader.get(
+    userName: 'RefactoringGuru',
+    repoName: 'design-patterns-dart',
+  );
+
+  print(
+    'Iterate last 10 commits.'
+        '\n----------------------------',
+  );
+
+  for (Commit commit in gitHubRepo.commitIterator()) {
+    print(commit.message);
+  }
+}
+```
+
+### Output:
+```
+Iterate last 10 commits.
+----------------------------
+Merge pull request #74 from ilopX/fix-conceptual-command-pattern-folder-name Fix conceptual command pattern folder name
+Fix conceptual command pattern folder name.
+Merge pull request #73 from ilopX/add-conceptual-command-pattern Add conceptual command pattern
+Bump version 0.35.0.
+Add README.
+Impl conceptual command pattern.
+Merge pull request #72 from ilopX/add-singleton-pattern Add singleton pattern.
+Bump version 0.34.0.
+Add README.
+```
+