tools: remove leftover license boilerplate

This last line was missed in 3e1b1dd

PR-URL: #3225
Reviewed-By: Ben Noordhuis <info@bnoordhuis.nl>

tools/doc/generate.js

@@ -1,5 +1,3 @@
-// USE OR OTHER DEALINGS IN THE SOFTWARE.
-
 var processIncludes = require('./preprocess.js');
 var marked = require('marked');
 var fs = require('fs');