(docs) Update CC7 instructions

documentation/docs/dev/index.md

@@ -69,23 +69,28 @@ dnf install --assumeyes make automake gcc gcc-c++ cmake git qt5  boost mercurial
 
 ### Centos7
 
-Packages shipped with Centos7, or installed by the YUM package manager, unfortunately are often too old. So, one needs to circumvent that, either by using pre-compiled bundles, RPMs, or building from sources.
+Packages shipped with Centos7, or installed by the YUM package manager, unfortunately are often too old. So, one needs to circumvent that, either by using pre-compiled bundles, or building from sources.
 
-For CMake, one way to easily set up a recent version of it, if one has CVMFS access, is the use of LCG bundles:
+#### Using the built-in third-party packages 
+
+For `Xerces-C`, `nlohmann-json`, `Coin3D`, `Simage`, and `SoQt`, one can use the built-in versions shipeed with GeoModel. They are tested and they avoid the installation from sources of all these packages.
+
+On Centos7, the GeoModel tools-suite, with support for the XML parser and the visualization tools, can be compiled (after having set a modern CMake) with:
 
 ```bash
-source /cvmfs/sft.cern.ch/lcg/views/LCG_100/x86_64-centos7-gcc9-opt/setup.sh
+cmake -DCMAKE_INSTALL_PREFIX=../install -DGEOMODEL_USE_BUILTIN_XERCESC=1 -DGEOMODEL_USE_BUILTIN_JSON=1 -DGEOMODEL_USE_BUILTIN_COIN3D=1 -DGEOMODEL_BUILD_VISUALIZATION=1 -DGEOMODEL_BUILD_TOOLS=1 ../GeoModel/
 ```
 
-For Xerces-C, nlohmann-json, Coin3D, Simage, and SoQt, one can use the built-in versions shipeed with GeoModel. They are tested and they avoid the installation from sources of all these packages.
+#### Using CVMFS and LCG
 
-On Centos7, the GeoModel tools-suite, with support for the XML parser and the visualization tools, can be compiled (after having set a modern CMake) with:
+If one has CVMFS access, one way to easily set up a recent version of CMake, Qt and the other packages, is the use of LCG bundles provided by the CERN "SFT" group:
 
 ```bash
-cmake -DCMAKE_INSTALL_PREFIX=../install -DGEOMODEL_USE_BUILTIN_XERCESC=1 -DGEOMODEL_USE_BUILTIN_JSON=1 -DGEOMODEL_USE_BUILTIN_COIN3D=1 -DGEOMODEL_BUILD_VISUALIZATION=1 -DGEOMODEL_BUILD_TOOLS=1 ../GeoModel/
+source /cvmfs/sft.cern.ch/lcg/views/LCG_100/x86_64-centos7-gcc9-opt/setup.sh
 ```
 
 
+
 ## Visualization 3D graphics dependencies
 
 ### 3D graphics dependencies - macOS
@@ -176,14 +181,14 @@ cd ..
 
 ## Quick instructions - Build everything
 
-With these instructions you will build the whole the whole software stack for GeoModel development. The GeoModel libraries will be built from the HEAD version of the 'master' branch. If something does not compile, please [let the developers' team know](../about/contacts.md). 
+With these instructions you will build the whole software stack for GeoModel development. The GeoModel libraries will be built from the HEAD version of the 'master' branch. If something does not compile, please [let the developers' team know](../about/contacts.md). 
 
 With these instructions, you will build: `GeoModelCore`, `GeoModelIO`, `GeoModelTools`, `GeoModelVisualization` (a.k.a., `gmex`).
 
 
 !!! note
 
-    These instructions will install the libraries and the tools in a **local** `install` folder. That is very useful for developmemnt, because yuo can handle multiple versions installed on the same system.
+    These instructions will install the libraries and the tools in a **local** `install` folder. That is very useful for developmemnt, because you can handle multiple versions installed on the same system.
 
     However, if you prefer to install the tools and the libraries in the `/usrl/local` system directory, just remove from the commands the option `-DCMAKE_INSTALL_PREFIX=../install`.