cmd/staticcheck: remove superfluous paragraph
@@ -19,9 +19,6 @@ const doc = `Usage of staticcheck:
The staticcheck command runs code analysis on one or more packages and
reports bugs, stylistic issues, unused identifiers and more.
-It provides the entry-point for a number of different check
-categories, which can be run simultaneously or individually.
-
Packages are specified in the same way as for your underlying build
system (e.g. go build, or Bazel).
