fix: update README to clarify package description and emphasize zero dependency

Author: c0rychu

README.md

@@ -3,7 +3,7 @@
 [![PyPI - Version](https://img.shields.io/pypi/v/physics-plot)](https://pypi.org/project/physics-plot/)
 [![PyPI - Downloads](https://img.shields.io/pypi/dm/physics-plot)](https://pypi.org/project/physics-plot/)
 
-`physics-plot` is a lightweight python package shipping a [Matplotlib style sheet](https://matplotlib.org/stable/gallery/style_sheets/style_sheets_reference.html) called [`pp_base.mplstyle`](https://github.com/c0rychu/physics-plot/blob/main/src/physics_plot/pp_base.mplstyle) and a few helper functions to create publication-quality plots with minimal effort.
+`physics-plot` is essentially a zero dependency python package shipping a Matplotlib style sheet — [`pp_base.mplstyle`](https://github.com/c0rychu/physics-plot/blob/main/src/physics_plot/pp_base.mplstyle) to create publication-quality plots with minimal effort. In addition, a few optional helper classes are provided.
 
 - [Documentation](https://c0rychu.github.io/physics-plot/)
 - [PyPI](https://pypi.org/project/physics-plot/)