Updated the capitalization in the titles

Some of the titles were inconsistent in capitalization.

README.md

@@ -30,7 +30,7 @@ https://github.com/thoughtbot/paperclip/releases
   - [Edit and New Views with Simple Form](#edit-and-new-views-with-simple-form)
   - [Edit and New Views with Simple Form](#edit-and-new-views-with-simple-form)
   - [Controller](#controller)
   - [Controller](#controller)
   - [View Helpers](#view-helpers)
   - [View Helpers](#view-helpers)
-  - [Checking a file exists](#checking-a-file-exists)
+  - [Checking a File Exists](#checking-a-file-exists)
   - [Deleting an Attachment](#deleting-an-attachment)
   - [Deleting an Attachment](#deleting-an-attachment)
 - [Usage](#usage)
 - [Usage](#usage)
 - [Validations](#validations)
 - [Validations](#validations)
@@ -40,7 +40,7 @@ https://github.com/thoughtbot/paperclip/releases
 - [Migrations](#migrations-1)
 - [Migrations](#migrations-1)
   - [Add Attachment Column To A Table](#add-attachment-column-to-a-table)
   - [Add Attachment Column To A Table](#add-attachment-column-to-a-table)
   - [Schema Definition](#schema-definition)
   - [Schema Definition](#schema-definition)
-  - [Vintage syntax](#vintage-syntax)
+  - [Vintage Syntax](#vintage-syntax)
 - [Storage](#storage)
 - [Storage](#storage)
   - [Understanding Storage](#understanding-storage)
   - [Understanding Storage](#understanding-storage)
 - [Post Processing](#post-processing)
 - [Post Processing](#post-processing)
@@ -261,7 +261,7 @@ end
 <%= image_tag @user.avatar.url(:thumb) %>
 <%= image_tag @user.avatar.url(:thumb) %>
 ```
 ```
 
 
-### Checking a file exists
+### Checking a File Exists
 
 
 There are two methods for checking if a file exists:
 There are two methods for checking if a file exists:
 
 
@@ -550,7 +550,7 @@ class AddAttachmentColumnsToUsers < ActiveRecord::Migration
 end
 end
 ```
 ```
 
 
-### Vintage syntax
+### Vintage Syntax
 
 
 Vintage syntax (such as `t.has_attached_file` and `drop_attached_file`) is still supported in
 Vintage syntax (such as `t.has_attached_file` and `drop_attached_file`) is still supported in
 Paperclip 3.x, but you're advised to update those migration files to use this new syntax.
 Paperclip 3.x, but you're advised to update those migration files to use this new syntax.