Add "Accessibility" tag to the "Web accessibility" module

Problem/Motivation

When searching for modules tagged with "Accessibility", this module didn't come up.

Steps to reproduce

Proposed resolution

Add "Accessibility" tag by editing the project.

Remaining tasks

Edit project and add tag.

User interface changes

Users will see the "Accessibility" tag on the project page and will be able to search for this module with that tag.

API changes

Data model changes