Documentation fullsimlight

This MR adds some documentation related to FullSimLight and its tools. It mainly adds a FullSimLight tools section (https://geomodel.web.cern.ch/geomodel/home/fullsimlight/fullsimlight/) that contains subsections explaining the use of the different tools (fullsimlight, gmclash, gmgeantino and gmtogdml). The How to build FullSimLight section is also moved under the For Developers section.

added Documentation label

added 54 commits

• 189788ef...505e6592 - 44 commits from branch master
• dc35f009 - How to build fullsimlight section moved under the 'For developers' section
• 7ab5ca84 - Add first skeleton of fullsimlight and tools documentation
• 93708cd5 - Fix typo in spelling the parallelepiped and moved section of GeoTrd where it...
• f4e8a7d2 - Documentation: Add fullsimlight application documentation
• 3cc41ae6 - Documentation: Add gmclash application documentation
• 35eddb7f - Documentation: Add gmgeantino application documentation
• d61bba19 - Documentation: Add gmtogdml application documentation
• 499eeb34 - Documentation: fix typos and inconsistencies
• 2977e7c8 - Documentation: correct the use of < and > symbols in MarkDown
• 6b0b2fc5 - Documentation: fix typos

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added 1 commit

• cc036793 - Documentation: modify size of images in gmclash documentation

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added 1 commit

• a0dea5cf - Documentation: Add CHEP2019 paper about FullSimLight

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added 1 commit

• 95bbcc12 - Documentation: fix typo

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merged

mentioned in commit 8932580b