Rollup merge of #35137 - jongiddy:explicit-wildcard, r=steveklabnik

Provide more explicit example of wildcard version in guessing game doc.

Beginners may try to adapt the tutorial to develop their own code.
When using different dependencies, they may use the wildcard for
versioning.  Since they are new to the language, they will not know
that the wildcard asterisk is a string, not a token.  Make the correct
format more explicit, to remove one potential source of frustration.