Upload README explaining purpose of code.

README.txt

+Title: Microtubule simulation code for "Measurements and simulations of microtubule growth imply 
+        strong longitudinal interactions and reveal a role for GDP on the elongating end"
+
+
+Overview:  These are the source codes for simulations of microtubule growth.
+
+
+##############################
+Programs are heirarchical:
+Smtll.m 
+Smtl.m 
+simulateMT_44.f90 (creates simulateMT_44.exe)
+
+Smtll.m runs Smtl.m, Smtl.m runs simulateMT_44.exe.
+
+Our system runs Red Hat Enterprise Linux Server 7.6 (Maipo)
+
+the following software is required (loaded as modules on our system)
+matlab2019a
+intel 15.0.0
+
+##############################
+The fortran executable can be run via command line to run a single, standalone simulation.
+Use Smtl to run replicates of a certain set of parameters.
+Use Smtll to run groups of Smtl objects.
+
+
+For the specific commands, please see the comments in each file.