update ch1.md in types & grammar

fixes two minor grammatical errors

types & grammar/ch1.md

@@ -248,7 +248,7 @@ function doSomethingCool() {
 }
 ```
 
-`doSomethingCool()` tests for a variable called `FeatureXYZ`, and if found, uses it, but if not, uses its own. Now, if someone includes this utility into their module/program, it safely checks if they've defined `FeatureXYZ` or not:
+`doSomethingCool()` tests for a variable called `FeatureXYZ`, and if found, uses it, but if not, uses its own. Now, if someone includes this utility in their module/program, it safely checks if they've defined `FeatureXYZ` or not:
 
 ```js
 // an IIFE (see "Immediately Invoked Function Expressions"
@@ -285,7 +285,7 @@ function doSomethingCool(FeatureXYZ) {
 }
 ```
 
-There's lots of options when designing such functionality. No one pattern here is "correct" or "wrong" -- there are various tradeoffs to each approach. But overall, it's nice that the `typeof` undeclared safety guard gives us more options.
+There are lots of options when designing such functionality. No one pattern here is "correct" or "wrong" -- there are various tradeoffs to each approach. But overall, it's nice that the `typeof` undeclared safety guard gives us more options.
 
 ## Review