Update first several paragraphs on index page of docs

docs/source/index.rst

@@ -12,21 +12,16 @@
 ModEM Documentation
 ===================
 
-Welcome to the ModEM's documentation! ModEM is a modular system for inversion of
-electromagnetic geophysical data.  
-
 ModEM was designed as a flexible electromagnetic modeling and inversion system,
-written in Fortran 95. Although the code can be (and has been) extended for
+written in Fortran 95. A primary design goal of the system was to allow
+simplified extension with regard to data types, modeling codes, parameterization
+and regularization, and inversion search algorithms (see Egbert and Kelbert,
+2012; Kelbert et al. 2014). Although the code can be (and has been) extended for
 inversion of more general types of EM data (e.g., controlled source, DC; see
 Meqbel and Ritter, 2015), here we describe the stable, core system developed for
-2D and 3D magnetotelluric (MT) problems.
-
-While a primary design goal of the system was to allow simplified extension with
-regard to data types, modeling codes, parameterization and regularization, and
-inversion search algorithms (see Egbert and Kelbert, 2012; Kelbert et al.
-2014). The stable MT program has a command-line interface, which controls
-available program options, and specifies required and optional input and output
-files.
+2D and 3D magnetotelluric (MT) problems. The stable MT program has a
+command-line interface, which controls available program options, and specifies
+required and optional input and output files.
 
 User's Guide
 ------------