doc : add a dot in hashmaps1.rs file to fill e.g.

exercises/11_hashmaps/hashmaps1.rs

@@ -3,7 +3,7 @@
 // A basket of fruits in the form of a hash map needs to be defined. The key
 // represents the name of the fruit and the value represents how many of that
 // particular fruit is in the basket. You have to put at least three different
-// types of fruits (e.g apple, banana, mango) in the basket and the total count
+// types of fruits (e.g. apple, banana, mango) in the basket and the total count
 // of all the fruits should be at least five.
 //
 // Make me compile and pass the tests!