Define a term in the FDC3 glossary that can be used to refer to the application definition format used by the App Directory

[kriswest]

Area of Issue

[x] App Directory

Issue Description:

The FDC3 App Directory standard incorporates both a definition of a REST API for interacting with a directory of applications and format for defining each individual application. Define a term in the FDC3 glossary that may be used to refer to the application definition.