Update README.md

Author: JanSlabon

README.md

@@ -1,2 +1,18 @@
 # FPDI-FPDF
-A kind of metadata package with fixed dependencies for the latest versions of FPDI and FPDF.
+A kind of metadata package for Composer with fixed dependencies for the latest versions of FPDI and FPDF.
+
+## Installation with [Composer](https://packagist.org/packages/setasign/fpdi-fpdf)
+
+```bash
+$ composer require "setasign/fpdi-fpdf": "1.5.4"
+```
+
+or you can include the following in your composer.json file:
+
+```json
+{
+    "require": {
+        "setasign/fpdi-fpdf": "1.5.4"
+    }
+}
+```