Fixed axios module default import name to match mock

[CatsOnFilm]

Why:

The example provides a declarative import name ("axiosMock") in
anticipation for it being mocked but doesn't actually use this name
in the mock.

• ...

This change addresses the need by:

• updates module name from axios -> axiosMock in Full Example snippet
• updates module name from axios -> axiosMock in Step-By-Step/Imports
  snippet

[alexkrolick]

I believe jest.mock takes the module name as a string, which is 'axios'

[CatsOnFilm]

Yes, you're right. My mistake. I thought it behaved differently and this wasn't clear from other examples (including Jest's docs), where the import is assigned the same name as the module name.