DOCS: readme updates

README.md

@@ -9,3 +9,28 @@ Add this crate to your `Cargo.toml`:
 ```toml
 [dependencies]
 timsrust = "x.x.x"
+```
+
+## Usage
+
+TimsRust is intended to be used as a library and not as a stand-alone application. An example of how to use it is found in e.g. [Sage](https://github.com/lazear/sage).
+
+### Basics
+
+Two primary data types are exposed through TimsRust:
+* Spectra: A traditional representation that expresses intensitites in function of mz values for a given precursor.
+* Frames: All recorded data from a single TIMS elution (i.e. at one specific retention_time).
+
+### File formats
+
+Two file formats are supported:
+* Bruker .d folder containing:
+    * analysis.tdf
+    * analysis.tdf_bin
+* Bruker .ms2 folder containing:
+    * converter.ms2.bin
+    * converter.MS2Spectra.ms2.parquet
+
+## Python bindings
+
+The [timsrust_pyo3](https://github.com/jspaezp/timsrust_pyo3) package is an example of how the performance of TimsRust can be utilized in Python