update install documentation to use swig version 4 or higher

We are not testing against swig version 3.x. Thus, we shouldn't claim we are keeping compatibility with that older version of swig.

Author: schaubh

docs/source/Install/installOnLinux.rst

@@ -18,7 +18,7 @@ In order to run Basilisk, the following software will be necessary. This documen
 
  - .. include:: ../bskPkgRequired.txt
 
-- `SWIG <http://www.swig.org/>`__ (version 3 or 4)
+- `SWIG <http://www.swig.org/>`__ (version 4.x)
 - `GCC <https://gcc.gnu.org/>`__
 - (Optional) Get the `GitKraken <https://www.gitkraken.com>`__
  application to be able to pull and manage a copy of Basilisk

docs/source/Install/installOnMacOS.rst

@@ -56,7 +56,7 @@ Install HomeBrew Support Packages
 #. Install `HomeBrew <http://brew.sh>`__ using a Terminal window and
  pasting the install script from the HomeBrew web site.
 
-#. The new SWIG version 4 is compatible with Basilisk. Install the SWIG software package using::
+#. SWIG version 4.X is compatible with Basilisk. Install the SWIG software package using::
 
  $ brew install swig
 
@@ -65,7 +65,6 @@ Install HomeBrew Support Packages
  $ brew install cmake
  $ brew link cmake
 
- You need at least version 3.14 or higher.
 
 Setting up the Python Environment
 ---------------------------------

docs/source/Install/installOnWindows.rst

@@ -18,7 +18,7 @@ In order to run Basilisk, the following software will be necessary:
 - `Python <https://www.python.org/downloads/windows/>`__ 3.8.x or greater
 - `pip <https://pip.pypa.io/en/stable/installing/>`__
 - Visual Studios 15 2017 or greater
-- `Swig <http://www.swig.org/download.html>`__ version 3 or 4
+- `Swig <http://www.swig.org/download.html>`__ version 4.X
 - (Optional) A GiT GUI application such as `GitKraken <https://www.gitkraken.com>`__
  to manage your copy of the Basilisk repository
 
@@ -53,7 +53,7 @@ required to place accurate breakpoints/attach a debugger to C/C++ code.
 
 Install Swig
 ~~~~~~~~~~~~
-The standard windows swig version 3 or 4 is suitable for Basilisk (see `Configuration
+The standard windows swig version 4 is suitable for Basilisk (see `Configuration
 Instructions <http://www.swig.org/Doc1.3/Windows.html#Windows_swig_exe>`__).
 Download the swig zip file, which includes ``swig.exe`` file, and unzip it into somewhere like ``C:/Program Files/Swig``