Update README.md

README.md

@@ -1,2 +1,19 @@
 # AssemblyNamespaceChanger
-Console utility to search/replace namespaces in .NET assemblies
+Console utility to search/replace namespaces in .NET assemblies.
+
+## Usage
+```
+  -i, --input      Required. Input assembly path.
+
+  -o, --output     Output assembly path. If not specified, '.Modified' will be
+                   added to the input assembly name.
+
+  -r, --regexps    Required. Array of regexp search and replace patterns. First
+                   consequential one is the search pattern, second is the
+                   replacement pattern. Separated by semicolon (:)
+```
+
+## Usage example
+```
+LostPolygon.AssemblyNamespaceChanger --input InputAssembly.dll --output Output/OutputAssembly.dll --regexps ^Foo:Bar.Foo:^Namespace1.Test:Namespace2:Whatever
+```