Add more details to the User Guide and Data Model docs about farm ass…

…ets.

docs/guide/mapping.md

@@ -20,6 +20,15 @@ designated as a location.
 When you're done modifying your area, remember to click the Save button at the
 bottom of the page to save your changes.
 
+## Farm Assets
+
+In some situations, it may be useful to organize Land Assets under one or more
+Farm Assets, which represent different locations or operations that are
+managed independently. farmOS includes a Farm Asset type in an optional module
+that can be turned on in those scenarios. Land Assets (and other locations) can
+be organized under Farm Assets in the location hierarchy to make their
+relationship clear.
+
 ## Map controls
 
 ### Zooming

docs/model/type/asset.md

@@ -26,7 +26,7 @@ included with farmOS define the following Asset types:
 - Water
 - Material
 - Group*
-- Farm
+- Farm*
 
 *Group Assets are unique in that they can "contain" other Assets as "group
 members". This is a flexible feature that can be used for many purposes. One
@@ -36,6 +36,11 @@ to see all the Groups that an Asset was a member of in the past, when/why they
 were moved, etc. See [farmOS Group Membership Logic](/model/logic/group) for
 more information.
 
+*Farm Assets can be used to model multiple "farms" within a single farmOS
+instance/dataset. This can be useful in situations where there are multiple
+different locations with their own Land Assets, Equipment Assets, etc, or as a
+place to store farm-level data that may not fit nicely in more granular records.
+
 ## ID
 
 Each Asset will be assigned two unique IDs in the database: a universally unique