Add workflow for assets

[jgvictores]

Workflow for assets when duplicates must be maintained, and specify these cases:

1. Generate sources, attempting to use open formats, for  example: .ods(see Attempt to standardize table formats #20) for tables (e.g. via calc), .svg for drawings (e.g. via inkscape), etc. Omit the next two steps if your format is not binary.
2. Upload to https://github.com/roboticslab-uc3m/teo-developer-manual -> assets/editable. Example: here.
3. Generate viewable contents, for  example: .md for tables (e.g. via ods2md)(see Attempt to standardize table formats #20), .png for drawings (e.g. via inkscape export option).
4. Upload to https://github.com/roboticslab-uc3m/teo-developer-manual -> assets. Example: here.
5. Link viewable contents within corresponding .md. Example: here.
6. Update external repositories that use this information (configuration files, simulation models...). Examples: teo-configuration-files, teo-openrave-models, teo-simox-models, teo_robot/teo-ros-simulation

[PeterBowman]

7. Update OR models?

[jgvictores]

7. Update OR models?

Updated issue description