Fix documentation for unknown arguments (#68)

Fixes the issue #68

docsite/source/index.html.md

@@ -8,7 +8,7 @@ name: dry-initializer
 sections:
   - container-version
   - params-and-options
-  - options-tolerance
+  - tolerance-to-unknown-arguments
   - optionals-and-defaults
   - type-constraints
   - readers

docsite/source/tolerance-to-unknown-arguments.html.md

@@ -0,0 +1,22 @@
+---
+title: Tolerance to Unknown Arguments
+layout: gem-single
+name: dry-initializer
+---
+
+By default the initializer is tolerant for both params (positional arguments) and options.
+All unknown arguments of the initializer are ignored silently.
+
+```ruby
+require 'dry-initializer'
+
+class User
+  extend Dry::Initializer
+end
+
+user = User.new 'Joe', role: 'admin'
+user.respond_to? :role # => false
+
+User.dry_initializer.attributes(user)
+# => {}
+```