message: Add to the glossary a definition for reality data
diff: @@ -75,6 +75,7 @@ tableRowAnchors: true
  | **Props** | iTwin.js uses the convention that the members and types of a *JSON wire format* are expressed in TypeScript by an [interface](https://www.typescriptlang.org/docs/handbook/interfaces.html) or [type alias](http://www.typescriptlang.org/docs/handbook/advanced-types.html) with the suffix **Props** (for *prop*erties). E.g. `ElementProps`, `ViewDefinitionProps`, etc. |
  | **Pull** | Process of downloading [Changesets](#changeset) for a [Briefcase](#briefcase) that are newer than the last Changeset [*merged*](#merge) into that Briefcase. |
  | **Push** | Process of uploading local changes from a [Briefcase](#briefcase) to [iModelHub](#imodelhub) in a form of a [Changeset](#changeset). It is necessary to [pull](#pull) and [merge](#merge) any newer changesets from other users before pushing. |
  +| **RealityData** | A digital representation of an asset generated from captured data of the physical asset, for example a 3D photogrammetric mesh model or a point cloud of a building. |
  | **RootSubject** | An Element in the iModel that describes (in text) the asset modeled by an iModel. There is always one and only one RootSubject. All information in an iModel will have some relationship to the RootSubject, making it the root of a *table of contents*. |
  | **RPC** | Remote procedure call. Allows a client to invoke an operation in a service. Web apps use HTTP to implement RPC calls, while desktop apps use pipes. |
  | **RpcInterface** | An interface exposed by a service and callable by clients via RPC. See [RpcInterface](../learning/RpcInterface.md) for more information. |
  