GLES2: Fix comments in previous commit that broke rendering (!)

Do NOT use "[vertex]" in a comment...

Kids, don't try to learn OpenGL on a production branch right before
a stable release.

drivers/gles2/shaders/canvas.glsl

@@ -221,7 +221,7 @@ VERTEX_SHADER_CODE
 [fragment]
 
 // texture2DLodEXT and textureCubeLodEXT are fragment shader specific.
-// Do not copy these defines in the [vertex] section.
+// Do not copy these defines in the vertex section.
 #ifndef USE_GLES_OVER_GL
 #ifdef GL_EXT_shader_texture_lod
 #extension GL_EXT_shader_texture_lod : enable

drivers/gles2/shaders/cubemap_filter.glsl

@@ -26,7 +26,7 @@ void main() {
 [fragment]
 
 // texture2DLodEXT and textureCubeLodEXT are fragment shader specific.
-// Do not copy these defines in the [vertex] section.
+// Do not copy these defines in the vertex section.
 #ifndef USE_GLES_OVER_GL
 #ifdef GL_EXT_shader_texture_lod
 #extension GL_EXT_shader_texture_lod : enable

drivers/gles2/shaders/scene.glsl

@@ -676,7 +676,7 @@ VERTEX_SHADER_CODE
 [fragment]
 
 // texture2DLodEXT and textureCubeLodEXT are fragment shader specific.
-// Do not copy these defines in the [vertex] section.
+// Do not copy these defines in the vertex section.
 #ifndef USE_GLES_OVER_GL
 #ifdef GL_EXT_shader_texture_lod
 #extension GL_EXT_shader_texture_lod : enable