docs: add module descriptions to overview

docs/overview.md

@@ -1,17 +1,34 @@
 # 🔎 Overview
 
-Antarctic-Plots
+Antarctic-Plots is a Python package developed to help with conducting Antarctic
+science. The 5 modules shown here provide tools to help with a variety of common
+tasks.
 
 ## Modules
 
-**Antarctic-Plots** consists of 5 modules:
+### Regions
+
+Pre-defined or interactively chosen geographic regions. Includes many ice
+shelves, glaciers, and general geographic regions. These can be used in
+functions throughout, such as subsetting data or specifying areas to plot.
 
 ### Fetch
 
+Easily download data sets to your computer, retrieve previously download data
+sets, and perform common gridded data manipulations. This module uses `Pooch` to
+managed the download, storage, and retrieve of data, and `PyGMT` for grid
+manipulations.
+
 ## Maps
 
+Create high-quality maps using PyGMT with functions specifically tailored to
+Antarctica. plot types: 2D, 3D, subplots, interactive maps
+
 ### Profile
 
-### Regions
+Define a line, sample layers & data along it, and plot the results.
 
 ### Utils
+
+Useful functions for common tasks: coordinate conversion, grid comparison,
+masking, de-trending.