Reduce "back to top" links to one per section

README.md

@@ -259,8 +259,6 @@ Below are the essential tags for basic, minimalist websites:
 - [All About Favicons (And Touch Icons)](https://bitsofco.de/all-about-favicons-and-touch-icons/)
 - [Favicon Cheat Sheet](https://github.com/audreyr/favicon-cheat-sheet)
 
-**[⬆ back to top](#table-of-contents)**
-
 ## Social
 
 ### Facebook Open Graph
@@ -280,8 +278,6 @@ Below are the essential tags for basic, minimalist websites:
 - [Facebook Open Graph Markup](https://developers.facebook.com/docs/sharing/webmasters#markup)
 - [Open Graph protocol](http://ogp.me/)
 
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 ### Facebook Instant Articles
 
 ``` html
@@ -298,8 +294,6 @@ Below are the essential tags for basic, minimalist websites:
 - [Facebook Instant Articles: Creating Articles](https://developers.facebook.com/docs/instant-articles/guides/articlecreate)
 - [Instant Articles: Format Reference](https://developers.facebook.com/docs/instant-articles/reference)
 
-**[⬆ back to top](#table-of-contents)**
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 ### Twitter Cards
 
 ``` html
@@ -315,8 +309,6 @@ Below are the essential tags for basic, minimalist websites:
 - [Twitter Cards: Getting Started Guide](https://dev.twitter.com/cards/getting-started)
 - [Twitter Card Validator](https://cards-dev.twitter.com/validator)
 
-**[⬆ back to top](#table-of-contents)**
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 ### Google+ / Schema.org
 
 ``` html
@@ -326,8 +318,6 @@ Below are the essential tags for basic, minimalist websites:
 <meta itemprop="image" content="https://example.com/image.jpg">
 ```
 
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 ### Pinterest
 
 Pinterest lets you prevent people from saving things from your website, according [to their help center](https://help.pinterest.com/en/articles/prevent-people-saving-things-pinterest-your-site). The `description` is optional.
@@ -336,8 +326,6 @@ Pinterest lets you prevent people from saving things from your website, accordin
 <meta name="pinterest" content="nopin" description="Sorry, you can't save from my website!">
 ```
 
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 ### OEmbed
 
 ``` html
@@ -385,8 +373,6 @@ Pinterest lets you prevent people from saving things from your website, accordin
 
 - [Apple Meta Tags](https://developer.apple.com/library/safari/documentation/AppleApplications/Reference/SafariHTMLRef/Articles/MetaTags.html)
 
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 ### Apple Safari
 
 ```html
@@ -394,8 +380,6 @@ Pinterest lets you prevent people from saving things from your website, accordin
 <link rel="mask-icon" href="/path/to/icon.svg" color="red">
 ```
 
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 ### Google Android
 
 ``` html
@@ -410,8 +394,6 @@ Pinterest lets you prevent people from saving things from your website, accordin
 <link rel="alternate" href="android-app://package-name/http/url-sample.com">
 ```
 
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 ### Google Chrome
 
 ``` html
@@ -421,8 +403,6 @@ Pinterest lets you prevent people from saving things from your website, accordin
 <meta name="google" content="notranslate">
 ```
 
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 ### Google Chrome Mobile (Android Only)
 
 Since Chrome 31, you can set up your web app to "app mode" like Safari.
@@ -441,8 +421,6 @@ Since Chrome 31, you can set up your web app to "app mode" like Safari.
 
 - [Google Developer](https://developer.chrome.com/multidevice/android/installtohomescreen)
 
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 ### Microsoft Internet Explorer
 
 ``` html
@@ -500,8 +478,6 @@ Since Chrome 31, you can set up your web app to "app mode" like Safari.
 <meta name="renderer" content="webkit|ie-comp|ie-stand">
 ```
 
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 ### QQ Mobile Browser
 
 ``` html
@@ -513,8 +489,6 @@ Since Chrome 31, you can set up your web app to "app mode" like Safari.
 <meta name="x5-page-mode" content="app">
 ```
 
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 ### UC Mobile Browser
 
 ``` html