Update features.md with warning 16

Author: alvaromontoro

features.md

@@ -41,4 +41,5 @@ A list of every a11y concern Checka11y.css will check for and highlight with lin
 - [W0012](./codes.md#W0012): Checks for heading element inside `<section>` element.
 - [W0013](./codes.md#W0013): Checks for anchor tags that contain a link to a PDF, Word, Excel, or PowerPoint document.
 - [W0014](./codes.md#W0014): Checks for anchor tags that contain a link to content site.
-- [W0015](./codes.md#W0014): Checks for images with the `longdesc` attribute.
+- [W0015](./codes.md#W0015): Checks for images with the `longdesc` attribute.
+- [W0016](./codes.md#W0016): Checks for zoom/scale being disabled in the meta `viewport`.