Update hooks.md (#616)

Author: cliffoo

README.md

@@ -547,7 +547,7 @@ function Foo() {
 
   useEffect(() => {
     // Note that ref.current may be null. This is expected, because you may
-    // conditionally render the ref-ed element, or you may forgot to assign it
+    // conditionally render the ref-ed element, or you may forget to assign it
     if (!divRef.current) throw Error("divRef is not assigned");
 
     // Now divRef.current is sure to be HTMLDivElement

docs/basic/getting-started/hooks.md

@@ -195,7 +195,7 @@ function Foo() {
 
   useEffect(() => {
     // Note that ref.current may be null. This is expected, because you may
-    // conditionally render the ref-ed element, or you may forgot to assign it
+    // conditionally render the ref-ed element, or you may forget to assign it
     if (!divRef.current) throw Error("divRef is not assigned");
 
     // Now divRef.current is sure to be HTMLDivElement