EUG - Review the usage of "stacks" and "workspaces"

These should be:

1. Properly defined in the glossary
2. Used correctly

Sometimes they are used interchangeably and the context doesn't make it clear why. Also, GUI elements of the dashboard should be referred to correctly

Some usage:
>In the Stack section, select the workspace runtime environment that will be used to build and run projects from the list.
>Start with a generic Java-based stack, then later add support for Node or Python.
>Select a stack from the Dashboard, then change the devfile to include your project

leads to a heading that talks about workspaces

Related issue: https://issues.redhat.com/browse/CRW-2096