add note about replicon integration

REPLICON_INTEGRATION.md

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+## Integrating bevy_timewarp with bevy_replicon
+
+I'm using [bevy_replicon](https://crates.io/crates/bevy_replicon) in my game, alongside bevy_timewarp.
+You can use custom deserializers with replicon to write updates into the `ServerSnapshot` buffer like this:
+
+### Custom timewarp deserializer example
+
+This is for [bevy_xpbd](https://crates.io/crates/bevy_xpbd_2d)'s `Rotation`` component:
+
+```rust
+pub fn deserialize_rotation_timewarp(
+    entity: &mut EntityMut,
+    _entity_map: &mut NetworkEntityMap,
+    mut cursor: &mut Cursor<Bytes>,
+    tick: RepliconTick,
+) -> Result<(), bincode::Error> {
+    let sin: f32 = bincode::deserialize_from(&mut cursor)?;
+    let cos: f32 = bincode::deserialize_from(&mut cursor)?;
+    let comp = Rotation::from_sin_cos(sin, cos);
+    if let Some(mut ss) = entity.get_mut::<ServerSnapshot<Rotation>>() {
+        ss.insert(tick.get(), comp);
+    } else {
+        entity.insert(comp);
+    }
+    if let Some(mut sync_status) = entity.get_mut::<SyncStatus>() {
+        sync_status.last_snapshot_rot = Some(comp);
+        sync_status.last_update_frame = tick.get();
+    }
+    Ok(())
+}
+
+pub fn serialize_rotation(
+    component: Ptr,
+    mut cursor: &mut Cursor<Vec<u8>>,
+) -> Result<(), bincode::Error> {
+    // SAFETY: Function called for registered `ComponentId`.
+    let comp: &Rotation = unsafe { component.deref() };
+    bincode::serialize_into(&mut cursor, &comp.sin())?;
+    bincode::serialize_into(&mut cursor, &comp.cos())
+}
+```