Update readme info

README.md

@@ -1,3 +1,20 @@
 # Oneroster API to CSV for ASM
 
-CSV SIS syncing tool for Apple Schools Manager from a Oneroster compliant API using CSV files
+A powershell script to create Apple School Manager compatible csv files
+from a Oneroster compliant API.
+
+## Usage
+
+Requires: Powershell Core
+
+```
+$VerbosePreference = 'continue'
+$env:GOORS_URL = 'https://my-oneroster-api/ims/oneroster/v1p1'
+$env:GOORS_CI = read-host #clientid
+$env:GOORS_CS = read-host #clientsecret
+
+. ConvertFrom-K12.ps1
+./sds-asm.ps1
+```
+
+Use sftp to drop the `csv-asm-$(unix-date).zip` file to your ASM sftp instance.