Episode 5: Typo in instructions for referring to commits

[dicksonlaw583]

In Episode 5, this is the wording for how to refer to commits by ID:

We can also refer to commits using those long strings of digits and letters that git log displays.

But git log has not been called thus far during the episode. I recommend amending this to git show, as that command is the most recently run and does contain the alphanumeric string mentioned.

If you are OK with this change, I can put in a PR for this on Thursday.