Add docs for new color and prefix settings.

README.md

@@ -51,6 +51,9 @@ Or install it yourself as:
     * [2.2.6 required](#226-required)
     * [2.2.7 validate](#227-validate)
     * [2.2.8 messages](#228-messages)
+    * [2.2.9 prefix](#229-prefix)
+    * [2.2.10 active_color](#2210-active_color)
+    * [2.2.11 help_color](#2211-help_color)
   * [2.3 keypress](#23-keypress)
   * [2.4 multiline](#24-multiline)
   * [2.5 mask](#25-mask)
@@ -335,6 +338,32 @@ prompt.ask('What is your email?') do |q|
 end
 ```
 
+### 2.2.9 prefix
+
+You can prefix each question asked using the `:prefix` option. This option can be applied either globally for all prompts or individual for each one:
+
+```ruby
+prompt = TTY::Prompt.new(prefix: '[?] ')
+```
+
+### 2.2.10 active_color
+
+All prompt types support `:active_color` option. In case of `select`, `multi_select`, `enum_select` or `expand` this color is used to highlight the currently selected choice. All the resulted inputs provided by user that are read in by the prompt as answer are highlighted with this color. This option can be applied either globablly for all prompts or individually.
+
+```ruby
+prompt.select('What size?', %w(Large Medium Small), active_color: :cyan)
+```
+
+Please (see pastel)[https://github.com/piotrmurach/pastel#3-supported-colors] for all supported colors.
+
+### 2.2.11 help_color
+
+Prompts such as `select`, `multi_select`, `expand` support `:help_color` which is used to customize the help text. This option can be applied either globablly for all prompts or individually.
+
+```ruby
+prompt.select('What size?', %w(Large Medium Small), help_color: :cyan)
+```
+
 ### 2.3 keypress
 
 In order to ask question with a single character or keypress answer use `keypress`: