docs: add doc comments to default_value helpers (#10437) (#11200)

Author: shashforge

crates/wasmtime/src/runtime/types.rs

@@ -2677,7 +2677,10 @@ impl GlobalType {
         };
         GlobalType::new(ty, mutability)
     }
+    /// Construct a new global import with this type’s default value.
     ///
+    /// This creates a host `Global` in the given store initialized to the
+    /// type’s zero/null default (e.g. `0` for numeric globals, `null_ref` for refs).
     pub fn default_value(&self, store: impl AsContextMut) -> Result<RuntimeGlobal> {
         let val = self
             .content()
@@ -2819,7 +2822,10 @@ impl TableType {
     pub(crate) fn wasmtime_table(&self) -> &Table {
         &self.ty
     }
+    /// Construct a new table import whose entries are filled with this type’s default.
     ///
+    /// Creates a host `Table` in the store with its initial size and element
+    /// type’s default (e.g. `null_ref` for nullable refs).
     pub fn default_value(&self, store: impl AsContextMut) -> Result<RuntimeTable> {
         let val: ValType = self.element().clone().into();
         let init_val = val
@@ -3160,7 +3166,10 @@ impl MemoryType {
     pub(crate) fn wasmtime_memory(&self) -> &Memory {
         &self.ty
     }
+    /// Construct a new memory import initialized to this memory type’s default state
     ///
+    /// Returns a host `Memory` in the given store with the configured initial
+    /// page size and zeroed contents.
     pub fn default_value(&self, store: impl AsContextMut) -> Result<RuntimeMemory> {
         RuntimeMemory::new(store, self.clone())
     }