fix: correct typos in doc comments for Engine, DebugInfo, and delegate call (#2591)

* chore: fix typo

* Update test_api.rs

* Update delegate.rs

Author: Snezhkko

crates/engine/src/ext.rs

@@ -81,7 +81,7 @@ impl Default for ChainSpec {
 }
 
 impl Engine {
-    // Creates a new `Engine instance.
+    // Creates a new `Engine` instance.
     pub fn new() -> Self {
         Self {
             database: Database::new(),

crates/engine/src/test_api.rs

@@ -57,7 +57,7 @@ impl Default for DebugInfo {
 }
 
 impl DebugInfo {
-    // Creates a new `RecInstance instance.
+    // Creates a new `RecInstance` instance.
     pub fn new() -> Self {
         Self {
             emitted_events: Vec::new(),

crates/env/src/call/call_builder/delegate.rs

@@ -174,7 +174,7 @@ where
     ///
     /// # Note
     ///
-    /// On failure this an [`ink::env::Error`][`crate::Error`] which can be handled by the
+    /// On failure this returns an [`ink::env::Error`][`crate::Error`] which can be handled by the
     /// caller.
     pub fn try_invoke(self) -> Result<ink_primitives::MessageResult<()>, Error> {
         self.params().try_invoke()