Create Tutorial - Learn to Determine How a Feature Works (End-to- End)

[U8NWXD]

Notes from Sean: This is a full-stack code tracing tutorial, can use some content from https://github.com/oppia/oppia/wiki/Find-the-right-code-to-change. Called “Trace code through all the frontend and backend layers to understand and describe how a feature works across these layers” in skill trees.

Try to pick an example that’s not necessarily 100% clear right off the bat, e.g. as exemplified in “Tips for analyzing the codebase” (https://github.com/oppia/oppia/wiki/Analyzing-the-Codebase).

Run a git patch file to repro oppia/oppia#17988

Reasoning: The solution changes are minimal here but debugging it is a bit tricky and it could be a good starting point to figure out repro steps from error logs.