Update doc comment

Author: aumetra

packages/vm-derive/src/lib.rs

@@ -11,9 +11,9 @@ macro_rules! maybe {
 use maybe;
 
 /// Hash the function
-/// 
+///
 /// # Example
-/// 
+///
 /// ```rust
 /// # use vm_derive::hash_function;
 /// #[hash_function(const_name = "HASH")]

packages/vm/src/modules/file_system_cache.rs

@@ -87,10 +87,22 @@ fn raw_module_version_discriminator() -> String {
     hasher.finalize().to_hex().to_string()
 }
 
-/// Bump this version whenever the module system changes in a way
+/// This version __MUST__ change whenever the module system changes in a way
 /// that old stored modules would be corrupt when loaded in the new system.
 /// This needs to be done e.g. when switching between the jit/native engine.
 ///
+/// By default, this derived by performing the following operation:
+///
+/// ```ignore
+/// BLAKE3(
+///   manual module version,
+///   wasmer version requirement,
+///   BLAKE3(cost_fn)
+/// )
+/// ```
+///
+/// If anything else changes, you must change the manual module version.
+///
 /// The string is used as a folder and should be named in a way that is
 /// easy to interpret for system admins. It should allow easy clearing
 /// of old versions.