Merge pull request #172 from jumpstarter-dev/glossary

Update glossary with definition for in-tree/out-of-tree standard/cust…

Author: mangelajo

docs/source/glossary.md

@@ -34,5 +34,14 @@ This project is still evolving, so these docs may be incomplete or out-of-date.
 * `Lease`: a time limited reservation of a exporter, a lease is created by a client
   and allows the client to use the exporter resources for a limited time.
 
-* `DriverClass`: is the name of the driver class that is used to interact with
+* `driver class`: is the name of the driver class that is used to interact with
   the exporter resources.
+
+* `driver client class`: is the name of the driver client class that is used directly
+  by end users, it interacts with `DriverClass` remotely via remote procedure call to
+  invoke `DriverClass` provided methods, which in turn interacts with the exporter resources.
+
+* `driver`: is the name for `driver class` and the corresponding `driver client class`, not to
+  be confused with `Driver`, the base class of all `driver class`. Drivers in the main `jumpstarter`
+  repo are called `in-tree drivers`, otherwise called `out-of-tree drivers`. Drivers implementing
+  predefined interfaces are called `standard drivers`, otherwise called `custom drivers`.