fix potential typo

src/content/chapter4_standard_library/lesson04_option_module/en.html

@@ -12,8 +12,8 @@
 
 <p>
   The option type is very similar to the result type, but it does not have an
-  error value. Some languages have functions return an option when there is no
-  extra error detail to give, but Gleam always uses result. This makes all
+  error value. Some languages have functions that return an option when there is
+  no extra error detail to give, but Gleam always uses result. This makes all
   fallible functions consistent and removes any boilerplate that would be
   required when mixing functions that use each type.
 </p>