Improve author link flexibility

Deprecate social networking links in `_config.yml` in favor or new `author.links` array for any link and in any order. All of Font Awesome's icons are available for use.

```
author:
  links:
    - label: "Your Website"
      icon: "fas fa-fw fa-link"
      url: "https://your-site.com"
    - label: "Twitter"
      icon: "fab fa-fw fa-twitter-square"
      url: "https://twitter.com/username"
    - label: "GitHub"
      icon: "fab fa-fw fa-github"
      url: "https://github.com/username"
    - label: "Instagram"
      icon: "fab fa-fw fa-instagram"
      url: "https://instagram.com/username"
```

Fixes #1581

docs/_docs/05-configuration.md

@@ -731,17 +731,42 @@ Used as the defaults for defining what appears in the author sidebar.
 
 ```yaml
 author:
-  name   : "Your Name"
-  avatar : "/assets/images/bio-photo.jpg"
-  bio    : "My awesome biography constrained to a sentence or two goes here."
-  email  : # optional
-  uri    : "http://your-site.com"
-  home   : # null (default), "absolute or relative url to link to author home"
+  name     : "Your Name"
+  avatar   : "/assets/images/bio-photo.jpg"
+  bio      : "My awesome biography constrained to a sentence or two goes here."
+  location : "Somewhere, USA" 
 ```
 
-Social media links are all optional, include the ones you want visible. In most cases you just need to add the username. If you're unsure double check `_includes/author-profile.html` to see how the URL is constructed.
+Author links are all optional, include the ones you want visible under the `author.links` array.
 
-To add social media links not included with the theme or customize the author sidebar further, read the full [layout documentation]({{ "/docs/layouts/#author-profile" | relative_url }}).
+| Name | Description |
+| --- | --- |
+| **label** | Link label (e.g. `"Twitter"`) |
+| **icon** | [Font Awesome icon](https://fontawesome.com/icons?d=gallery) classes (e.g. `"fab fa-fw fa-twitter-square"`) |
+| **url** | Link URL (e.g. `"https://twitter.com/mmistakes"`) |
+
+```yaml
+author:
+  name: "Your Name"
+  avatar: "/assets/images/bio-photo.jpg"
+  bio: "I am an amazing person."
+  location: "Somewhere"
+  links:
+    - label: "Made Mistakes"
+      icon: "fas fa-fw fa-link"
+      url: "https://mademistakes.com"
+    - label: "Twitter"
+      icon: "fab fa-fw fa-twitter-square"
+      url: "https://twitter.com/mmistakes"
+    - label: "GitHub"
+      icon: "fab fa-fw fa-github"
+      url: "https://github.com/mmistakes"
+    - label: "Instagram"
+      icon: "fab fa-fw fa-instagram"
+      url: "https://instagram.com/mmistakes"
+```
+
+To customize the author sidebar, read the full [layout documentation]({{ "/docs/layouts/#author-profile" | relative_url }}).
 
 ## Reading Files