Clean up doc of search option "path"
Clean up doc of search option "path"

- Examples should use "path" instead of "file"
- Double quotation isn't required

Release-Notes: skip
Google-Bug-Id: n/a
Change-Id: I685fddc1509ba7440a50ed9627ea0553fb180a68

GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit,GerritCodeReview/gerrit