contrib: Update snippets

Author: claremacrae

contributing/Testing/Using Obsidian API in tests.md

@@ -64,7 +64,7 @@ Obtain all the `Task` objects from all the Markdown files:
 
 <!-- snippet: readAllTasksFromAllSimulatedFiles -->
 ```ts
-const tasks = readAllTasksFromAllSimulatedFiles();
+const allTasks = readAllTasksFromAllSimulatedFiles();
 ```
 <!-- endSnippet -->