ER — Error in definition of Activity

There was an error made in a recent change to the definition of Activity. Please return the definition to the original, "An activity defines one or more kinds of work items and gives guidance on how to perform these"

The current definition refers to work products which is wrong because an activity does not require a work product.

Update glossary and language specification descriptions

The changes given in this resolution make, the descriptions in the language consistent with the definition in Clause 4, without using the term “work item”, which is not actually defined in the language.