Edited the introduction to the overview.

The current introduction talks about a stack. I understand the intention of teaching new students a lingo, but no overview about libraries is given. My current edit can help students get an understanding of what content follows.

core/overview.md

@@ -1,9 +1,7 @@
 # Overview
 
-A group of programs that works in tandem to produce a result or achieve a common goal is often referred to as a software stack.
-This page gives an overview of the Python geoscience stack.
-Scroll to the end of the page for cross-referenced tutorial material for several of the packages in the stack.
-We suggest that new users start with the [Foundational Skills](../foundations/overview) section in order to get the most out of these tutorials.
+As you might know by now that Python is a programming language. To make your job easier, developers of this programming language provide users like you with libraries (or packages). Core libraries will help you with fundamental numerical functions, and high-level libraries will help you efficiently analyze and visualize your data. Some of these libraries are used all across the Python community, while others are domain-specific. Read below to learn more about core and high-level libraries, and domain-specific libraries of the geoscience community. We suggest that new users start with the [Foundational Skills](../foundations/overview) section in order to get the most out of the tutorials below. 
+
 
 ## Core libraries