Symbol and format fix.

#### grunt.config.md

This Gruntfile really means "the Gruntfile", so use `Gruntfile` may be better? And there are many cases like this in other files e.g. grunt.file.md.

> File paths are relative to the `Gruntfile` unless the current working directory is changed with `grunt.file.setBase` or the `--base` command-line option.

> Change grunt's current working directory (CWD). By default, all file paths are relative to the `Gruntfile`.

#### grunt.util.md

Step 2 use colon to connect goal and method, so step 1 use it too may be better?