add a few instructions on how to use `komodo`

README.md

 # Komodo: Cryptographically-proven Erasure Coding
+
+## Usage
+Komodo can either be used as a library or as a binary application.
+
+## the library
+see `cargo doc`
+
+## the binary application
+below is an example of how to use the binary application with Nushell:
+```bash
+use komodo.nu [
+    "komodo build",
+    "komodo setup",
+    "komodo prove",
+    "komodo verify",
+    "komodo reconstruct",
+]
+use binary.nu [ "bytes decode" ]
+
+let bytes = open komodo.nu
+
+komodo build
+
+komodo setup $bytes
+
+komodo prove $bytes --fec-params {k: 3, n: 5}
+komodo verify blocks/0.bin blocks/1.bin
+
+(komodo reconstruct blocks/0.bin blocks/2.bin blocks/3.bin | bytes decode) == $bytes
+```
+
+`true` should be printed at the end :thumbsup: