Auto merge of #207 - nkanderson:fix_iterators2, r=komaeda

Fix iterators2

A couple of small changes to the `iterators2` exercise. @Jesse-Cameron, it looks like you contributed this exercise, so I wanted to check and see if these changes are in line with your intentions. Happy to adjust if they're not :)

Author: bors

exercises/standard_library_types/iterators2.rs

@@ -1,15 +1,15 @@
 // iterators2.rs
 // In this module, you'll learn some of unique advantages that iterators can offer
 // Step 1. Complete the `capitalize_first` function to pass the first two cases
-// Step 2. Apply the `capitalize_first` function to a vector of strings, ensuring that it
+// Step 2. Apply the `capitalize_first` function to a vector of strings, ensuring that it returns a vector of strings as well
 // Step 3. Apply the `capitalize_first` function again to a list, but try and ensure it returns a single string
 // As always, there are hints below!
 
 pub fn capitalize_first(input: &str) -> String {
     let mut c = input.chars();
     match c.next() {
         None => String::new(),
-        Some(first) => first.collect()::<String>() + c.as_str(),
+        Some(first) => first.collect::<String>() + c.as_str(),
     }
 }