Make uniform references names and sections

[JamieBort]

Specifically, make references to branch names, lesson sections, and assignment sections all uniform.

For example, in Assignment 6: Prisma ORM Integration,

• Assignment 6a, assignment6a, and assignment 6a are all appear in the document.
• As does "assignment6b branch " and "assignment6b branch".

[JamieBort]

Assuming this repo is obsolete, this Issue can be closed.
@jrmcgarvey