Fix README in lookup data
The binary in this directory checks the correctness of the lookup data file.
-Usage:
+Usage (e.g., after running `./scripts/docker_sh`):
```bash
-./scripts/docker_run RUST_LOG=debug cargo run --manifest-path=oak_functions/lookup_data_checker/Cargo.toml -- --file-path=weather_data_file
+RUST_LOG=debug cargo run --manifest-path=oak_functions/lookup_data_checker/Cargo.toml -- --file-path=oak_functions/examples/weather_lookup/testdata/lookup_data_weather_sparse_s2
+```
+
+to get
+
+```bash
+...
+[36.9581960, 149.3685880], [36.9108250, 148.8116340], [143.1569150, -30.9774870]]} # Cell ID
+[2023-01-12T13:02:18Z DEBUG lookup_data_checker] - {[66.2241310, -162.2377160]: [123, 34, 116, 101, 109, 112, 101, 114, 97, 116, 117, 114, 101, 95, 100, 101, 103, 114, 101, 101, 115, 95, 99, 101, 108, 115, 105, 117, 115, 34, 58, 49, 55, 125]} # Location
+[2023-01-12T13:02:18Z INFO lookup_data_checker] Format is correct
```
