add some more doc comments

Author: buffalojoec

builtins/src/prototype.rs

@@ -1,14 +1,22 @@
+//! Prototype layouts for builtins.
+
 use {
     crate::core_bpf_migration::CoreBpfMigrationConfig,
     solana_program_runtime::invoke_context::BuiltinFunctionWithContext, solana_pubkey::Pubkey,
 };
 
 /// Transitions of built-in programs at epoch boundaries when features are activated.
 pub struct BuiltinPrototype {
+    /// Configurations for migrating the builtin to Core BPF.
     pub core_bpf_migration_config: Option<CoreBpfMigrationConfig>,
+    /// Feature ID that enables the builtin program.
+    /// If None, the built-in program is always enabled.
     pub enable_feature_id: Option<Pubkey>,
+    /// The program's ID.
     pub program_id: Pubkey,
+    /// The program's name, ie "system_program".
     pub name: &'static str,
+    /// The program's entrypoint function.
     pub entrypoint: BuiltinFunctionWithContext,
 }
 
@@ -29,7 +37,10 @@ impl std::fmt::Debug for BuiltinPrototype {
 /// is reserved.
 #[derive(Debug)]
 pub struct StatelessBuiltinPrototype {
+    /// Configurations for migrating the stateless builtin to Core BPF.
     pub core_bpf_migration_config: Option<CoreBpfMigrationConfig>,
+    /// The program's ID.
     pub program_id: Pubkey,
+    /// The program's name, ie "feature_gate_program".
     pub name: &'static str,
 }