chore: add a release note to the changelog

CHANGELOG.md

@@ -2,8 +2,29 @@
 
 Integraal aims to provide generic and efficient tools for numerical integration in the Rust Programming Language.
 
---- 
+---
 
-## To be released
+## 0.1.0
+
+Integraal's first (real) release is here!
+
+The crate features a main structure, `Integraal`, that acts as the entrypoint for your numerical integration.
+You can specify the domain and the function of the integral, as well as the numerical integration method using
+methods of the structure. It follows a builder-like pattern.
+
+Domains and functions are described using struct enums for the sake of flexibility. The repository contains
+usage examples for both analytical expression and sampled values integration. The following numerical
+integration methods are implemented:
+
+- Riemann summation (both left rule and right rule)
+- Trapezoid rule
+- Simpson's rule (different variants depending on the domain & function)
+- Boole's rule
+- Romberg's rule
+- Monte Carlo method
+
+Different methods have different requirements and dependencies. All of this is detailed in the documentation.
+
+In the future, the computation kernel may support different execution backends. This would align with the initial
+motivation behind this crate, that is being an experiment over flexible API designs for HPC.
 
-A feature list will be written for the first non-alpha release (i.e. `0.1.0`)