update README with examples

Author: GregHanson

README.md

@@ -2,6 +2,52 @@
 
 This Rust-based tool converts JSON data into RDF format, utilizing the `oxrdf` crate for RDF graph handling and `serde_json` for efficient JSON parsing. It supports lightweight, memory-efficient processing by reading JSON data values sequentially, which makes it suitable for large datasets.
 
+## Using the json2rdf CLI
+
+This library includes a CLI utility for parsing JSON and generating N-Triple RDF using the `convert` subcommand. The binary can be built using `cargo build`.
+
+```bash
+$ json2rdf convert --help
+Convert JSON to RDF format.
+
+The `convert` command parses a JSON file, converts it to RDF triples using `serde_json` for parsing and `oxrdf` to construct the graph, and saves the output.
+
+Usage: json2rdf convert [OPTIONS] --json-files <JSON_FILES>
+
+Options:
+  -n, --namespace <NAMESPACE>
+          Namespace for RDF graph generation.
+
+          A custom namespace to prefix RDF resources created from JSON keys and values.
+
+  -j, --json-files <JSON_FILES>
+          Path to input JSON file(s).
+
+          Provide the path to one or more JSON files that will be parsed and converted.
+
+  -o, --output-file <OUTPUT_FILE>
+          Path to output file.
+
+          Optional: Specify the path to save the generated RDF data.
+
+  -h, --help
+          Print help (see a summary with '-h')
+```
+
+## Using the convert library
+
+The conversion functionality can also be called directly in Rust. The library supports writing results to a file or building an in-memory `oxrdf::Graph`.
+
+```rust
+use json2rdf::json_to_rdf;
+
+// capture conversion results to file
+let results = json_to_rdf(&"tests/airplane.json".to_string(), &Some("http://example.com/ns#".to_string()), &Some("output.nt".to_string()));
+
+// capture conversion results to an oxrdf::Graph
+let results = json_to_rdf(&"tests/airplane.json".to_string(), &Some("http://example.com/ns#".to_string()), &None);
+```
+
 ## License
 
 This project is licensed under either of