Update docs for max_heap_size

Author: rscarson

examples/max_heap_size.rs

@@ -13,7 +13,7 @@ fn main() -> Result<(), Error> {
     );
 
     let mut runtime = Runtime::new(RuntimeOptions {
-        max_heap_size: Some(1 * 1024 * 1024),
+        max_heap_size: Some(5 * 1024 * 1024),
         ..Default::default()
     })?;
 

src/inner_runtime.rs

@@ -126,6 +126,11 @@ pub struct RuntimeOptions {
     pub timeout: Duration,
 
     /// Optional maximum heap size for the runtime
+    ///
+    /// If the heap size is exceeded, the runtime will return a `HeapExhausted` error.
+    ///
+    /// **WARNING** this is not a minimum heap size; the underlying V8 isolate will still crash if this number is too small for startup
+    /// (~5mb with default features)
     pub max_heap_size: Option<usize>,
 
     /// Optional cache provider for the module loader