TASK: Add and update glossary

[YojanaGadiya]

Issues should resolve the following:

• [x] Completion of the definition of terms within the glossary
• [x] Updation of terms with respect to DSM v3.0
• [x] Deployment of the glossary on the GitHub pages
• [ ] Linking of the DSM tool with the glossary terms

[YojanaGadiya]

The last item has been moved to the DSM tool repository.