Update README.md

Author: RobynLlama

README.md

@@ -1,2 +1,21 @@
 # TSValidatorCLI
+
 A small commandline tool to validate thunderstore packages locally before upload
+
+## Usage
+
+Use `--help` to see all command line switches. Default use is `-f <foldername>` to validate all files contained in the package.
+
+## Current Validations
+
+- Manifest.json is present
+  - And valid JSON
+  - And Contains all required keys
+  - [Warn] And does not contain the `installers` key (unused)
+ 
+- Icon.png is present
+  - And contains a valid IHDR header
+  - And has the correct width&height
+
+- [Warn] License is present
+- [Warn] Changelog.md is present