Update README.md

Author: marcelmaatkamp

README.md

@@ -1,12 +1,26 @@
 # StringFormatter
 
+# install
+
+Add dependeny in pom.xml:
+
+```xml
+<dependency>
+  <groupId>nl.marcelmaatkamp</groupId>
+  <artifactId>stringformatter</artifactId>
+  <version>${{  github.ref_name }}</version>
+</dependency>
+```
+
+## usage
+
 ```java
 String result = nl.maatkamp.stringformatter.StringFormatter.of(
   "{1} {ham} {0} {foo} {1}")
     .arg(10)
     .arg(20)
     .arg("foo", "bar")
     .arg("ham", "spam")
-  .format();
+      .format();
 // Output: "20 spam 10 bar 20"
 ```