Add details on new dependencies

documentation/docs/dev/build_fullsimlight.md

-
 # How to build FullSimLight
 
+# Prerequisites
+FullSimLight depends on Geant4, Xerces-C and HDF5. Additionally, the user might want to install [Pythia8] (http://home.thep.lu.se/Pythia/ ) and [HepMC3](https://gitlab.cern.ch/hepmc/HepMC3) as optional dependencies.
+
 # Standard build
 
 FullSimLight can be built as part of the GeoModel build, by enabling the related configuration flag `GEOMODEL_BUILD_FULLSIMLIGHT`:
@@ -35,7 +37,7 @@ ls ../install
 
 ## How to use a custom version of Xerces-C
 
-The Geant4 GDML format depends on teh Xerces-C library. Therefore, different Geant4 releases can use different versions of the Xerecs-C library.
+The Geant4 GDML format depends on the Xerces-C library. Therefore, different Geant4 releases can use different versions of the Xerces-C library.
 
 If you want to build FullSimLight with a custom, locally installed Xerces-C library, you can pass the `XercesC_INCLUDE_DIR` and `XercesC_LIBRARY` variable to CMake while configuring the build of FullSimLight:
 

documentation/docs/fullsimlight/atlas-extensions/index.md

@@ -7,6 +7,7 @@ If you still didn't clone the repository you can clone it recursively:
 ```c++
 git clone --recursive https://gitlab.cern.ch/GeoModelDev/GeoModel.git
 ```
+
 Alternatively, if you already cloned the GeoModel repository, it will be sufficient to type the following commands from the main repository folder:
 
 ```c++
@@ -20,7 +21,7 @@ A flag is available to build the ATLAS extentions (by default OFF) and it should
 cmake ../ -DGEOMODEL_BUILD_ATLASEXTENSIONS=ON
 ```
 
-A configuration file {{atlas-conf.json}} with all the ATLAS specific customizations is provided with the ATLASExtensions and will be installed under {{<install>/share/FullSimLight/ATLAS}}. In order to run a Geant4 ATLAS with your favourite geometry tag you only have to run the following:
+A configuration file **atlas-conf.json** with all the ATLAS specific customizations is provided with the ATLASExtensions and will be installed under **<install>/share/FullSimLight/ATLAS**. In order to run a Geant4 ATLAS with your favourite geometry tag you only have to run the following:
 ```c++
 ./fullSimLight  -g geometry.db -c atlas-conf.json
 ```

documentation/docs/fullsimlight/fullsimlight/index.md

@@ -8,6 +8,8 @@ FullSimLight package consists of different tools based on [Geant4](https://geant
 - gmgeantino: a tool to generate geantino maps from your input geometry
 - gm2gdml: a tool to convert geometries and dump them in gdml format.
 
+For instructions on how to build FullSimLight, please refer to the [Build FullSimLight ](https://geomodel.web.cern.ch/home/dev/build_fullsimlight/) page. 
+
 ## Detector Construction
 
 ### Geometry:
@@ -17,13 +19,15 @@ Use the -g flag to specify the name of the input geometry file.
 
 ### ATLAS Geometry Files:
 
-The .gdml and .SQLite files of ATLAS geometry tags ATLAS-R2-2016-01-00-01 are available at: 
+At installation time an ATLAS geometry file and the ATLAS Magnetic field map file will be automatically downloaded and installed under *< path-to-install >/share/FullSimLight/ATLAS* if the user will activate the `GEOMODEL_INSTALL_FSLDATA` flag at compile time. 
 
+Additional .gdml and .SQLite files of ATLAS geometry tag ATLAS-R2-2016-01-00-01 are available at: 
+s
 ```bash
 wget https://gitlab.cern.ch/GeoModelATLAS/geometry-data/raw/master/geometry/geometry-ATLAS-R2-2016-01-00-01.gdml  
 wget https://geomodel.web.cern.ch/atlas-geometry-data/geometry-ATLAS-R2-2016-01-00-01.db 
 ```
-For instructions on how to produce your own SQLite dump of your preferred ATLAS geometry tag, please have a look at the ATLAS Extensions section.
+For instructions on how to produce your own SQLite dump of your preferred ATLAS geometry tag, please refet to the [ATLAS Extensions](https://geomodel.web.cern.ch/home/fullsimlight/atlas-extensions/) page.
 
 
 ## FullSimLight: run and options