Improve accessibility of navigation menu button

Add `type` and label text.

Fixes #1099

Update CHANGELOG and history

Update CHANGELOG and history

Fix system font rendering in Chrome on macOS/OS X (#1290)

Use `BlinkMacSystemFont` instead of private font name.

Closes #1289

Fix param name from pt-BR locale (#1279)

Update CHANGELOG and history

Add missing Brazilian Portuguese text strings translations (#1278)

Improve translation in pt-br

There are some issues in the brazilian portuguese translation:

```  
less_than                  : "meno que" 
```

the word "meno" doesn't exist in the language, the correct translation is "menos"

```
  minute_read                : "minuto(s) de leitura" 
```

once we can one or more minutes of reading, the plural of the word "minuto" is optional, so we can use "(s)" after the word "minuto" to reflect this

```
 related_label              : "Talvez você goste também" 
```

this change is for better reading, the previous translation is not good

I changed the capitalization of the subsequent words for lowercase to have default capitalization in all translations.

Add note about Staticman GitHub compatibility

Staticman only works with GitHub hosted repositories. This enhancement to the theme's documentation makes that clear.

Close #1273

Clarify theme gem migration documentation

Include asset folders that should be removed when migrating from a "forked theme".

Close #1268

Update CHANGELOG and history

Add alt description to avatar image

Use author's name as `alt` description  in comment avatar image.

Use archive page screenshots instead of post

Update README

- Edit notable features
- Add skin screenshots

Release 4.6.0 :gem:

Reference GitHub comment

Update CHANGELOG and history

Add `pre` to version

Update Magnific Popup to v1.1.0

Update jQuery Smooth Scroll to v2.2.0