cotton: add page (#3312)

pages/common/cotton.md

@@ -0,0 +1,16 @@
+# cotton
+
+> Markdown test specification runner.
+> More information: <https://github.com/chonla/cotton>.
+
+- Use a specific base url:
+
+`cotton -u {{base_url}} {{file}}.md`
+
+- Disable certificate verification (insecure mode):
+
+`cotton -u {{base_url}} -i {{file}}.md`
+
+- Stop running when a test fails:
+
+`cotton -u {{base_url}} -s {{file}}.md`