update readme

readme.md

+First module for docxtemplater.
+
+# Installation:
+
+You will need docxtemplater v1: `npm install docxtemplater@beta`
+
+install this module: `npm install docxtemplater-image-module`
+
+# Usage
+
+Your docx should contain the text: `{%image}`
+
+    ImageModule=require(‘docxtemplater-image-module’)
+
+    imageModule=new ImageModule({centered:false})
+
+    docx=new DocxGen()
+        .attachModule(imageModule)
+        .load(content)
+        .setData({image:'examples/image.png'})
+        .render()
+
+    buffer= docx
+            .getZip()
+            .generate({type:"nodebuffer"})
+
+    fs.writeFile("test.docx",buffer);
+
+# Options
+
+ You can center the images using new ImageModule({centered:true}) instead
+
+# Notice
+
+ For the imagereplacer to work, the image tag: `{%image}` need to be in its own `<w:p>`, so that means that you have to put a new line after and before the tag.