Fix broken link & Add Baidu site verification (mmistakes#3139)

* Fix broken link
Link to Bing Webmaster Tools was broken.

* Fix broken link
Link to Open Graph debug tool was broken.

* Add Baidu site verification (mmistakes#2830)
Added `baidu_site_verification` to `_config.yml`

_config.yml

@@ -73,8 +73,9 @@ google:
 # SEO Related
 google_site_verification :
 bing_site_verification   :
-yandex_site_verification :
 naver_site_verification  :
+yandex_site_verification :
+baidu_site_verification  :
 
 # Social Sharing
 twitter:

docs/_config.yml

@@ -66,8 +66,9 @@ algolia:
 # SEO Related
 google_site_verification : "UQj93ERU9zgECodaaXgVpkjrFn9UrDMEzVamacSoQ8Y" # Replace this with your ID, or delete
 bing_site_verification   :
-yandex_site_verification :
 naver_site_verification  :
+yandex_site_verification :
+baidu_site_verification  :
 
 # Social Sharing
 twitter:

docs/_docs/05-configuration.md

@@ -711,7 +711,7 @@ Formerly known as [Google Webmaster Tools](https://www.google.com/webmasters/too
 
 #### Bing Webmaster Tools
 
-There are several ways to [verify site ownership](https://www.bing.com/webmaster/help/how-to-verify-ownership-of-your-site-afcfefc6) --- the easiest adding an authentication code to your config file.
+There are several ways to [verify site ownership](https://www.bing.com/webmasters/help/add-and-verify-site-12184f8b) --- the easiest adding an authentication code to your config file.
 
 Copy and paste the string inside of `content`:
 
@@ -808,7 +808,7 @@ facebook:
   username: "michaelrose"  # https://www.facebook.com/michaelrose
 ```
 
-**ProTip:** To debug Open Graph data use [this tool](https://developers.facebook.com/tools/debug/og/object?q=https%3A%2F%2Fmademistakes.com) to test your pages. If content changes aren't reflected you will probably have to hit the **Fetch new scrape information** button to refresh.
+**ProTip:** To debug Open Graph data use [this tool](https://developers.facebook.com/tools/debug/) to test your pages. If content changes aren't reflected you will probably have to hit the **Scrape Again** button to refresh.
 {: .notice--info}
 
 ##### Open Graph default image