[Docs: Rewrite] Unexplained switch to separate <PostExcerpt> component usage

[sysrage]

What docs page needs to be fixed?

• Section: Redux Essentials
• Page: Async Logic and Data Fetching

What is the problem?

In the section "Displaying Loading State", the example code suddenly switches to using <PostExcerpt>, but that wasn't used in the last set of instructions where this portion of code is used. Anybody following-along the guide is forced to scroll to the bottom of this section to open the code sandbox and see exactly how the <PostExcerpt> component is built. The code sandbox from the previous section didn't include <PostExcerpt> as a separate component.

Users can ignore this and continue using the single-component layout, but it makes things a bit confusing when they get to the profiling section and don't see a separate <PostExcerpt> component. It also makes it difficult to then wrap React.memo() around it.

What should be changed to fix the problem?

Use the separate <PostExcerpt> component in the previous section.

[markerikson]

Hmm. I know I went back and forth on whether to have that component a few times while writing the tutorial. It's very possible that I didn't end up showing that one clearly.

[markerikson]

Resolved by #4153