Update README.md

README.md

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 ## epcqrcode
 
-An EPC-QRCode generator in ERPNext for creating QRCodes, e.g., on sales invoices.
+An EPC-QRCode generator in ERPNext.
+
+EPC-QRCodes (European Payments Council Quick Response Codes) are used to initiate SEPA credit transfers.
+They encode all necessary data (IBAN, amount, recipient) and may be placed on invoices to eliminate the error-prone typing of payment Information.
+
+## Installation
+
+From the frappe-bench folder, execute
+
+    $ bench get-app https://github.com/bytegrasp/epcqrcode.git
+    $ bench --site YOUR_SITE install-app epcqrcode
+
+where `YOUR_SITE` is e.g. erp.example.com
+
+## Usage
+
+After installing the custom app, an HTTP endpoint for generating EPC-QRCodes as PNG images will be available in your ERPNext instance under `/api/method/epcqrcode.generator.get_code`.
+The endpoint directly serves PNG images and takes the following query parameters to generate the QRCode
+
+* name: the recipients name
+* iban: the recipients International Bank Account Number (IBAN)
+* bic: the recipients Bank Identifier Code (BIC), optional and only required for non-EEA countries
+* amount: the amount to transfer in EUR (no other currencies are supported by EPC-QRCodes)
+* text: the remittance information (either text or reference required)
+* reference: the remittance information (either text or reference required)
+* purpose: the SEPA purpose code (optional)
+* scale: the scaling factor number for sizing the generated QRCode (optional)
+* border: the border size number which adds padding to the generated QRCode (optional)
+
+You can use this endpoint as source to an image, e.g., within a custom HTML print format, to place an EPC-QRCode in your sales invoice.
+With this, you can also make use of Jinja template variables, e.g., to use the sales invoice number as payment reference in the QRCode.
+
+```
+<div style="margin-top: 10px;">
+  <img width="110" height="110" src="/api/method/epcqrcode.generator.get_code?name=Your+Company&reference={{ doc.name }}&iban=AT026000000001349870&amount={{ doc.grand_total }}&scale=4&border=0">
+  <p>Zahlen mit QR-Code</p>
+</div>
+```
+
+## Update
+
+From the frappe-bench folder, run updates with 
+
+    $ bench update
+
+## Compatibility
+
+The custom app is tested against ERPNext v13.26.0.
+
+## License 
+
+MIT License, refer to LICENSE
+
+The copyright is owned by Bytegrasp OG and contributors. 
+The software comes as-is without any warranty.