Documenting changes

Author: jbogard

docs/source/15.0-Upgrade-Guide.md

@@ -14,4 +14,32 @@ services.AddAutoMapper(cfg => {
 });
 ```
 
-You can register for your license at [https://automapper.io](https://automapper.io).
+You can register for your license at [https://automapper.io](https://automapper.io).
+
+## Breaking Changes
+
+### `AddAutoMapper`
+
+With the requirement to supply a license, the `AddAutoMapper` overloads all require the `Action<IMapperConfigurationExpression>` parameter:
+
+```c#
+// Previous
+services.AddAutoMapper(typeof(Program));
+
+// Current
+services.AddAutoMapper(cfg => cfg.LicenseKey = "<License Key Here>", typeof(Program));
+```
+
+This method parameter is first for all `AddAutoMapper` overloads.
+
+### `MapperConfiguration`
+
+The constructor to `MapperConfiguration` now requires an `ILoggerFactory`:
+
+```c#
+public MapperConfiguration(
+    MapperConfigurationExpression configurationExpression, 
+    ILoggerFactory loggerFactory)
+```
+
+This parameter is used for diagnostics.