bump version to 1.3.1

update README to match changes

README.md

@@ -21,29 +21,25 @@ repositories {
 }
 
 dependencies {
-    implementation("com.infendro:cli:1.3.0")
+    implementation("com.infendro:cli:1.3.1")
 }
 ```
 
 ## Usage
 
 ```kotlin
-import com.infendro.cli.argument.stringOrElse
-import com.infendro.cli.argument.stringOrNull
-import com.infendro.cli.command.cli
-
 fun main(args: Array<String>) {
     // declare root command
     cli {
         execute {
-            // execution of root command (e.g., display help)    
+            // execution of root command (e.g., display help)
         }
 
         // declare command "test"
         command("test") {
             // declare arguments
-            val greetingArg = stringOrElse("greeting", "Hello")
-            val nameArg = stringOrNull("name")
+            val greetingArg = stringOrElse("greeting", "greet", "g", other = "Hello")
+            val nameArg = stringOrNull("name", "n")
 
             execute {
                 // retrieve the arguments