Issue on page /user_guide/coordinate_systems.html
I wonder if ti would be good idea to add a table comparing the properties of the 3 coordinates systems like.
Some of the properties could be names of the axis, its value, origin of the system, typical uses of the system (within Harmonica/Fatiando?).
Maybe something like this: in rst format (I think)
+------------+----------------------+---------------------------+------------------------+ | Axis | Cartesianas (planas) | Geodeticas / geographical | Spherical (geocentric) | +---+--------+----------------------+---------------------------+------------------------+ | 1 | Name | easting | longitude | +---+--------+----------------------+----------------------------------------------------+ | 1 | Symbol | x | \lambda | +---+--------+----------------------+----------------------------------------------------+ | 1 | Unit | m | decimal degrees | +---+--------+----------------------+---------------------------+------------------------+ | 2 | Name | northing | latitude | spherical latitude | +---+--------+----------------------+---------------------------+------------------------+ | 2 | Symbol | y | \varphi | \phi | +---+--------+----------------------+---------------------------+------------------------+ | 2 | Unit | m | decimal degrees | +---+--------+----------------------+---------------------------+------------------------+ | 3 | Name | upward | height | radio | +---+--------+----------------------+---------------------------+------------------------+ | 3 | Symbol | z | h | r | +---+--------+----------------------+---------------------------+------------------------+ | 3 | Unit | m | +---+--------+---------------------------------------------------------------------------+