tiny changes: spelling and consistency

[tylerl]

Spelling: optimzed -> optimized

Consistency: Import * -> Import "*"

For consistency with Import "as" and Export "as". Also -- as-is it looks like Import * is just Import with a footnote. It had me confused for several minutes.

NB: This shouldn't affect links, since neither * nor quotes are reflected in the link fragment. The URL is simply /import-export#import either way.

[CLAassistant]

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