New term for glossary - virtual operation

[TimCliff]

Developers who are working with the Steem blockchain are likely to come across virtual operations. It would be helpful to define what these are.

[inertia186]

Virtual operations are listed at the bottom: https://developers.steem.io/apidefinitions/#apidefinitions-broadcast-ops

[TimCliff]

The recommendation is to define what a virtual operation is in the glossary. It is likely that when a lot of developers come across those methods, they will not know what a "virtual operation" is.

[inertia186]

Yep, makes sense.