Update README.md

Author: drinkingkazu

README.md

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+More verbose how to will follow...
+
+## How to run G4 
+- You would need a local build of `edep-sim` forked [here](https://github.com/drinkingkazu/edep-sim)
+  - You can use the `develop.sif` neutrino image (as of 2025-04-08 pointing to `larcv2_ub2204-cuda121-torch251-larndsim.sif` )
+- Necessary configuration files can be found under [generator](https://github.com/DeepLearnPhysics/simlar/tree/main/generator)
+
+Example how to:
+```
+edep-sim -g geometry/BigLArCube.gdml -e 100 -o generator.h5 biglarbox.mac
+```
+Look though the contents of `biglarbox.mac`. For most users, the only part to change is the yaml file argument in the line below
+```
+/generator/kinematics/bomb/config mpvmpr_ccmu.yaml
+```
+which is a [DLPGenerator](https://github.com/DeepLearnPhysics/DLPGenerator) configuration yaml file.
+
+### How to run a detector simulation
+
+Example how to:
+```
+simlar-run.py run_develop --input_file generator.h5 --output_file detsim.h5
+```
+
+