Fix some outdated file reference comments in bevy_pbr (#6111)

# Objective

Simple docs/comments only PR that just fixes some outdated file references left over from the render rewrite.

## Solution

- Change the references to point to the correct files

crates/bevy_pbr/src/render/light.rs

@@ -163,7 +163,7 @@ impl GpuPointLights {
     }
 }
 
-// NOTE: These must match the bit flags in bevy_pbr2/src/render/pbr.frag!
+// NOTE: These must match the bit flags in bevy_pbr/src/render/mesh_view_types.wgsl!
 bitflags::bitflags! {
     #[repr(transparent)]
     struct PointLightFlags: u32 {
@@ -184,7 +184,7 @@ pub struct GpuDirectionalLight {
     shadow_normal_bias: f32,
 }
 
-// NOTE: These must match the bit flags in bevy_pbr2/src/render/pbr.frag!
+// NOTE: These must match the bit flags in bevy_pbr/src/render/mesh_view_types.wgsl!
 bitflags::bitflags! {
     #[repr(transparent)]
     struct DirectionalLightFlags: u32 {

crates/bevy_pbr/src/render/mesh.rs

@@ -112,7 +112,7 @@ pub struct MeshUniform {
     pub flags: u32,
 }
 
-// NOTE: These must match the bit flags in bevy_pbr2/src/render/mesh.wgsl!
+// NOTE: These must match the bit flags in bevy_pbr/src/render/mesh_types.wgsl!
 bitflags::bitflags! {
     #[repr(transparent)]
     struct MeshFlags: u32 {

crates/bevy_pbr/src/render/mesh_view_types.wgsl

@@ -41,7 +41,7 @@ struct DirectionalLight {
 let DIRECTIONAL_LIGHT_FLAGS_SHADOWS_ENABLED_BIT: u32 = 1u;
 
 struct Lights {
-    // NOTE: this array size must be kept in sync with the constants defined bevy_pbr2/src/render/light.rs
+    // NOTE: this array size must be kept in sync with the constants defined in bevy_pbr/src/render/light.rs
     directional_lights: array<DirectionalLight, 1u>,
     ambient_color: vec4<f32>,
     // x/y/z dimensions and n_clusters in w