csslint: add page (#1723)

pages/common/csslint.md

@@ -0,0 +1,27 @@
+# csslint
+
+> A linter for CSS code.
+
+- Lint a single CSS file:
+
+`csslint {{file.css}}`
+
+- Lint multiple CSS files:
+
+`csslint {{file1.css}} {{file2.css}} {{file3.css}}`
+
+- List all possible style rules:
+
+`csslint --list-rules`
+
+- Specify certain rules as errors (which result in a non-zero exit code):
+
+`csslint --errors={{errors,universal-selector,imports}} {{file.css}}`
+
+- Specify certain rules as warnings:
+
+`csslint --warnings={{box-sizing,selector-max,floats}} {{file.css}}`
+
+- Specify certain rules to completely ignore:
+
+`csslint --ignore={{ids,rules-count,shorthand}} {{file.css}}`