Adding README.md to FlattenForFSRoot

Author: Harsimran Singh

FlattenForFSRoot/README.md

@@ -0,0 +1,36 @@
+# Introduction
+
+Following is the documentation on how to build ```FlattenForFSRoot``` in your own work directory in JLab's ifarm account.
+
+# Prerequisites
+
+Make sure that GlueX environment is set up. It is typically set by adding following lines in the ```.cshrc``` file if not already present.
+
+```
+setenv BUILD_SCRIPTS /group/halld/Software/build_scripts
+source $BUILD_SCRIPTS/gluex_env_jlab.csh
+```
+
+# Installation
+
+1. Move into the directory where you want to build it:
+```
+cd /path/to/work/directory
+```
+
+2. Clone the ```hd_utilities``` GitHub repository: 
+```
+git clone https://github.com/JeffersonLab/hd_utilities
+```
+
+3. Move into ```FlattenForFSRoot``` directory:
+```
+cd hd_utilities/FlattenForFSRoot/
+```
+
+4. Make sure there is a ```Makefile``` in this directory. Finally, run:
+```
+make
+```
+
+5. After this is complete, there will be a newly formed executable named ```flatten```.