Explain LOD arguments in Shading language (#6593)

Fixes https://github.com/godotengine/godot-docs/issues/3904

tutorials/shaders/shader_reference/shading_language.rst

@@ -1160,8 +1160,8 @@ is used, it can be scalar or vector.
 +-----------------------------------------------------------------------------+---------------------------------------------------------------------+
 | ivec2 **textureSize** (gsampler2D s, int lod)                               | Get the size of a texture.                                          |
 |                                                                             |                                                                     |
-| ivec3 **textureSize** (gsampler2DArray s, int lod)                          |                                                                     |
-|                                                                             |                                                                     |
+| ivec3 **textureSize** (gsampler2DArray s, int lod)                          | The LOD defines which mipmap level is used. An LOD value of 0 will  |
+|                                                                             | use the full resolution texture.                                    |
 | ivec3 **textureSize** (gsampler3D s, int lod)                               |                                                                     |
 |                                                                             |                                                                     |
 | ivec2 **textureSize** (samplerCube s, int lod)                              |                                                                     |
@@ -1202,8 +1202,8 @@ is used, it can be scalar or vector.
 +-----------------------------------------------------------------------------+---------------------------------------------------------------------+
 | gvec4_type **textureLod** (gsampler2D s, vec2 p, float lod)                 | Perform a texture read at custom mipmap.                            |
 |                                                                             |                                                                     |
-| gvec4_type **textureLod** (gsampler2DArray s, vec3 p, float lod)            |                                                                     |
-|                                                                             |                                                                     |
+| gvec4_type **textureLod** (gsampler2DArray s, vec3 p, float lod)            | The LOD defines which mipmap level is used. An LOD value of 0.0     |
+|                                                                             | will use the full resolution texture.                               |
 | gvec4_type **textureLod** (gsampler3D s, vec3 p, float lod)                 |                                                                     |
 |                                                                             |                                                                     |
 | vec4 **textureLod** (samplerCube s, vec3 p, float lod)                      |                                                                     |
@@ -1212,8 +1212,8 @@ is used, it can be scalar or vector.
 +-----------------------------------------------------------------------------+---------------------------------------------------------------------+
 | gvec4_type **textureProjLod** (gsampler2D s, vec3 p, float lod)             | Performs a texture read with projection/LOD.                        |
 |                                                                             |                                                                     |
-| gvec4_type **textureProjLod** (gsampler2D s, vec4 p, float lod)             |                                                                     |
-|                                                                             |                                                                     |
+| gvec4_type **textureProjLod** (gsampler2D s, vec4 p, float lod)             | The LOD defines which mipmap level is used. An LOD value of 0.0     |
+|                                                                             | will use the full resolution texture.                               |
 | gvec4_type **textureProjLod** (gsampler3D s, vec4 p, float lod)             |                                                                     |
 +-----------------------------------------------------------------------------+---------------------------------------------------------------------+
 | gvec4_type **textureGrad** (gsampler2D s, vec2 p, vec2 dPdx,                | Performs a texture read with explicit gradients.                    |
@@ -1238,8 +1238,8 @@ is used, it can be scalar or vector.
 +-----------------------------------------------------------------------------+---------------------------------------------------------------------+
 | gvec4_type **texelFetch** (gsampler2D s, ivec2 p, int lod)                  | Fetches a single texel using integer coordinates.                   |
 |                                                                             |                                                                     |
-| gvec4_type **texelFetch** (gsampler2DArray s, ivec3 p, int lod)             |                                                                     |
-|                                                                             |                                                                     |
+| gvec4_type **texelFetch** (gsampler2DArray s, ivec3 p, int lod)             | The LOD defines which mipmap level is used. An LOD value of 0 will  |
+|                                                                             | use the full resolution texture.                                    |
 | gvec4_type **texelFetch** (gsampler3D s, ivec3 p, int lod)                  |                                                                     |
 +-----------------------------------------------------------------------------+---------------------------------------------------------------------+
 | gvec4_type **textureGather** (gsampler2D s, vec2 p [, int comps])           | Gathers four texels from a texture.                                 |