Document usage of IDynamicParameters in more detail (#1707)

Considering all of the inquiries on StackOverflow about DynamicParameters, there should probably be a simple overview in the documentation.
Examples:

- https://stackoverflow.com/questions/12723922/dapper-adddynamicparams-for-in-statement-with-dynamic-parameter-name
- https://stackoverflow.com/questions/43412455/dapper-with-sql-query-dynamic-parameters
- https://stackoverflow.com/questions/38443739/passing-dynamically-created-sql-parameters-into-dapper-as-an-anonymous-type
- https://stackoverflow.com/questions/62448900/how-do-i-loop-through-dapper-dynamic-query-results-using-strings-as-parameters
- https://stackoverflow.com/questions/36735189/dapper-dynamicparameters-returning-error

Author: bigjonroberts

Readme.md

@@ -187,12 +187,35 @@ Alternatively, you might prefer Frans Bouma's [RawDataAccessBencher](https://git
 Parameterized queries
 ---------------------
 
-Parameters are passed in as anonymous classes. This allow you to name your parameters easily and gives you the ability to simply cut-and-paste SQL snippets and run them in your db platform's Query analyzer.
+Parameters are usually passed in as anonymous classes. This allow you to name your parameters easily and gives you the ability to simply cut-and-paste SQL snippets and run them in your db platform's Query analyzer.
 
 ```csharp
 new {A = 1, B = "b"} // A will be mapped to the param @A, B to the param @B
 ```
+Parameters can also be built up dynamically using the DynamicParameters class. This allows for building a dynamic SQL statement while still using parameters for safety and performance.
 
+```csharp
+    var sqlPredicates = new List<string>();
+    var queryParams = new DynamicParameters();
+    if (boolExpression)
+    {
+        sqlPredicates.Add("column1 = @param1");
+        queryParams.Add("param1", dynamicValue1, System.Data.DbType.Guid);
+    } else {
+        sqlPredicates.Add("column2 = @param2");
+        queryParams.Add("param2", dynamicValue2, System.Data.DbType.String);
+    }
+```
+
+DynamicParameters also supports copying multiple parameters from existing objects of different types.
+    
+```csharp
+    var queryParams = new DynamicParameters(objectOfType1);
+    queryParams.AddDynamicParams(objectOfType2);
+```
+    
+When an object that implements the `IDynamicParameters` interface passed into `Execute` or `Query` functions, parameter values will be extracted via this interface. Obviously, the most likely object class to use for this purpose would be the built-in `DynamicParameters` class.
+    
 List Support
 ------------
 Dapper allows you to pass in `IEnumerable<int>` and will automatically parameterize your query.