Fix some comments

interfaces/13-io/main.go

@@ -54,7 +54,7 @@ func main() {
 }
 
 // ioCopy streams from a file to another file.
-// we use it to stream from the standard input to ouput.
+// we use it to stream from the standard input to output.
 func ioCopy(dst, src *os.File) error {
 	// Use a fixed-length buffer to efficiently read from src stream in chunks.
 	buf := make([]byte, 32768)

interfaces/14-io-reusable/main.go

@@ -33,7 +33,7 @@ func transfer() (n int64, err error) {
 }
 
 // ioCopy streams from a file to another file.
-// we use it to stream from the standard input to ouput.
+// we use it to stream from the standard input to output.
 func ioCopy(dst, src *os.File) error {
 	// Use a fixed-length buffer to efficiently read from src stream in chunks.
 	buf := make([]byte, 32768)

x-tba/slicing-allocs-gotcha/main.go

@@ -61,7 +61,7 @@ func report() {
 	r()
 
 	runtime.GC()
-	fmt.Print(" > After Garbage Colletion  : ")
+	fmt.Print(" > After Garbage Collection  : ")
 	r()
 }