Edit first paragraph under "Light nodes" (#2245)

* Edit first paragraph under "Light nodes"

Edited the first paragraph under "Light nodes" for concision. Removed the first part of the second sentence. Instead of noting that lights are discussed later in the article, added internal links.

* Grammar fixes in Threadsafe APIs

Edited structure of the first and third sentences to improve flow. Corrected "multi threading" to "multithreading"

* Revert "Grammar fixes in Threadsafe APIs"

This reverts commit 696a05420f655dfd551c0205e0be78eb5a143d3b.

tutorials/3d/lights_and_shadows.rst

@@ -22,10 +22,9 @@ in the :ref:`doc_spatial_material` tutorial.
 Light nodes
 -----------
 
-As mentioned before, there are three types of light nodes: Directional,
-Omni and Spot. Each has different uses and will be described in
-detail below, but first let's take a look at the common parameters for
-lights:
+There are three types of light nodes: `Directional light`_,
+`Omni light`_ and `Spot light`_. Let's take a look at the common 
+parameters for lights:
 
 .. image:: img/light_params.png