updated README

README.md

@@ -1 +1,15 @@
 # esm2markdown
+
+This python script is intended to be used to automatically generate use case / correlation rule documentation in Markdown format for the McAfee Enterprise Sceurity Manager (ESM). It accepts a XML file that has been exported from the correlation rule editor of the ESM, converts its contents to Markdown format and writes it into a new file. If you need any other format, you might want to use pandoc to convert to e.g. pdf, docx or HTML.
+
+## Usage
+
+```
+python esm2markdown <rule xml file> <markdown output file>
+```
+
+## Example
+
+```
+python esm2markdown RuleExport_2018_03_01_12_36_37.xml documentation.mk
+```