Add config docs about environment variables

[ylvaselling]

Got tired of having to look for the environment variables in the source code, so I decided to write up a quick docs page for it.

[alexanderbock]

Suggested change

	- `OPENSPACE_GLOBEBROWSING` If this environment variable is set, the OpenSpaceData folder which normally is placed one level above the OpenSpace folder, can be placed anywhere on your computer. This folder stored all the map data from planets. This is very handy if you are using multiple versions of OpenSpace, for the following reasons:
	- `OPENSPACE_GLOBEBROWSING`: If this environment variable is set, the `OpenSpaceData` folder which normally is placed one level above the OpenSpace folder, can be placed anywhere on your computer. This folder stored all the map data from planets. This is very handy if you are using multiple versions of OpenSpace, for the following reasons:

[WeirdRubberDuck]

Suggested change

	- `OPENSPACE_GLOBEBROWSING` If this environment variable is set, the OpenSpaceData folder which normally is placed one level above the OpenSpace folder, can be placed anywhere on your computer. This folder stored all the map data from planets. This is very handy if you are using multiple versions of OpenSpace, for the following reasons:
	- `OPENSPACE_GLOBEBROWSING`: If this environment variable is set, the `OpenSpaceData` folder (which normally is placed one level above the OpenSpace folder) can be placed anywhere on your computer. This folder stores all the map data from planets. This is very handy if you are using multiple versions of OpenSpace, for the following reasons:

A bit unsure about the formulation "This folder stores all the map data form planets". Not obvious to me what that means. And it's not all the data, right?

[ylvaselling]

Any suggestions how to make this clearer?

[WeirdRubberDuck]

How about removing the empty line after each point? makes no difference in the output

Also, Mr @alexanderbock usually wants the list indented one step, so I guess that should be done for this file as well (?)

[WeirdRubberDuck]

This link does not work.

[ylvaselling]

It works for me
https://openspace--39.org.readthedocs.build/39/using-openspace/configuration/index.html#environment-variables

[WeirdRubberDuck]

Interesting. Did not work in my local build

Feel free to ignore then :)

[WeirdRubberDuck]

Suggested change

	- `OPENSPACE_GLOBEBROWSING` If this environment variable is set, the OpenSpaceData folder which normally is placed one level above the OpenSpace folder, can be placed anywhere on your computer. This folder stored all the map data from planets. This is very handy if you are using multiple versions of OpenSpace, for the following reasons:
	- `OPENSPACE_GLOBEBROWSING`: If this environment variable is set, the `OpenSpaceData` folder (which normally is placed one level above the OpenSpace folder) can be placed anywhere on your computer. This folder stores all the map data from planets. This is very handy if you are using multiple versions of OpenSpace, for the following reasons:

A bit unsure about the formulation "This folder stores all the map data form planets". Not obvious to me what that means. And it's not all the data, right?