`init`: Fix typo in comment

In the `init` script, I had written “mis-mash” where I meant to write
“mish-mash”.

This commit fixes this typo, changing the term to “mishmash”.

I omitted the U+002D HYPHEN-MINUS in the corrected version for two
reasons:

  - “mish-mash” is listed as a mere alternative spelling of “mishmash”
    in Wiktionary, and my Vim setup does not recognize it as a word; and

  - leaving the hyphen-minus in while adding the ‘h’ would have pushed
    the line over my hard-wrapping boundary, resulting in it being split
    into two lines — a waste of space, when the hyphenated version isn’t
    even the more correct.