DOCS: Add notes for new features in v3.1.0.

Author: baagaard-usgs

docs/user/coordsys.md

@@ -150,6 +150,10 @@ cs._configure()
 
 ## CSGeoLocal
 
+:::{note}
+New in v3.1.0.
+:::
+
 `CSGeoLocal` provides the flexibility of adding a local origin and rotation to a georeferenced coordinate system.
 As with `CSGeo`, we use [Proj](https://proj.maptools.org) to perform georeferenced coordinate system operations, so any geographic coordinate system supported by Proj can be used.
 See the [Proj documentation](https://proj.org/development/reference/functions.html#c.proj_create) for more information.

docs/user/spatialdb/analyticdb.md

@@ -1,5 +1,10 @@
 # AnalyticDB
 
+:::{note}
+New in v3.1.0.
+:::
+
+
 If the values for a field can be described by an analytic function, such as a polynomial `f(x) = a * x + b`, then you should use an `AnalyticDB`.
 In addition to the analytical expressions for the fields, you also need to provide the name and units for each field, and the coordinate system (the default is `CSCart`).