Add different types of volumes to the glossary (docker#2831)

* add different types of volumes to the glossary

* clarify details about different types of volumes

_data/glossary.yaml

@@ -295,3 +295,14 @@ volume: |
   delete volumes when you remove a container, nor will it "garbage collect"
   volumes that are no longer referenced by a container.
   *Also known as: data volume*
+
+  There are three types of volumes: *host, anonymous, and named*:
+
+  - A **host volume** lives on the Docker host's filesystem and can be accessed from within the container.  
+
+  - A **named volume** is a volume which Docker manages where on disk the volume is created,
+    but it is given a name.
+
+  - An **anonymous volume** is similar to a named volume, however, it can be difficult, to refer to
+    the same volume over time when it is an anonymous volumes. Docker handle where the files are stored.
+