Improve TextSpan documentation

[gwafotapa]

Objective

The example in the documentation of TextSpan is wrong. It correctly states that Text or Text2d must be present but won't use either leading to no rendering. It also states that TextLayout, TextFont and TextColor of the first span will all set default values for the children, which is not true. TextLayout determines the layout of the block but each node has its own TextFont and TextColor which are both required components of TextSpan.

The type description is not clear about Text or Text2d being mandatory.

Solution

• Fix the documentation