Make README more accessible to novices (#2042)

* Make README more accessible to novices

* Amend per @JonRowe's review

* Apply second round of fixes per @JonRowe's review

* Amend per @benoittgt's code review

* Remove trailing whitespace

* Apply more fixes per @JonRowe's review

* Change semicolon to full colon in intro

* Fix punctuation in intro

* Apply changes per @samphippen's review

* Fix description of spec type assignment, per @JonRowe's suggestion

* Rephrase introduction per @mikegee's review

Author: rlue

features/matchers/have_http_status_matcher.feature

@@ -1,12 +1,16 @@
 Feature: `have_http_status` matcher
 
   The `have_http_status` matcher is used to specify that a response returns a
-  desired status code.
+  desired status code. It accepts one argument in any of the following formats:
+
+  * numeric code
+  * status name as defined in `Rack::Utils::SYMBOL_TO_STATUS_CODE`
+  * generic status type (`:success`, `:missing`, `:redirect`, or `:error`)
 
   The matcher works on any `response` object. It is available for use in
   [controller specs](../controller-specs), [request specs](../request-specs), and [feature specs](../feature-specs).
 
-  Scenario: Checking a numeric response code
+  Scenario: Checking a numeric status code
     Given a file named "spec/controllers/application_controller_spec.rb" with:
       """ruby
       require "rails_helper"
@@ -31,7 +35,7 @@ Feature: `have_http_status` matcher
     When I run `rspec spec`
     Then the examples should all pass
 
-  Scenario: Checking a symbolic response code
+  Scenario: Checking a symbolic status name
     Given a file named "spec/controllers/application_controller_spec.rb" with:
       """ruby
       require "rails_helper"
@@ -56,7 +60,7 @@ Feature: `have_http_status` matcher
     When I run `rspec spec`
     Then the examples should all pass
 
-  Scenario: Checking a general response code
+  Scenario: Checking a symbolic generic status type
     Given a file named "spec/controllers/application_controller_spec.rb" with:
       """ruby
       require "rails_helper"

features/view_specs/view_spec.feature

@@ -1,6 +1,26 @@
 Feature: view spec
 
-  View specs live in spec/views and render view templates in isolation.
+  View specs are marked by `:type => :view`
+  or if you have set `config.infer_spec_type_from_file_location!`
+  by placing them in `spec/views`.
+
+  Use them to test the content of view templates
+  without invoking a specific controller.
+  They generally follow three steps:
+
+  ```ruby
+  assign(:widget, Widget.new)  # sets @widget = Widget.new in the view template
+
+  render
+
+  expect(rendered).to match(/text/)
+  ```
+
+  1. Use the `assign` method to set instance variables in the view.
+
+  2. Use the `render` method to render the view.
+
+  3. Set expectations against the resulting rendered template.
 
   Scenario: View specs render the described view file
     Given a file named "spec/views/widgets/index.html.erb_spec.rb" with:
@@ -73,6 +93,34 @@ Feature: view spec
     When I run `rspec spec/views`
     Then the examples should all pass
 
+  Scenario: View specs can render templates in layouts
+    Given a file named "spec/views/widgets/widget.html.erb_spec.rb" with:
+      """ruby
+      require "rails_helper"
+
+      RSpec.describe "rendering the widget template" do
+        context "with the inventory layout" do
+          it "displays the widget" do
+            assign(:widget, Widget.create!(:name => "slicer"))
+
+            render :template => "widgets/widget.html.erb", :layout => "layouts/inventory"
+
+            expect(rendered).to match /slicer/
+          end
+        end
+      end
+      """
+    And a file named "app/views/widgets/widget.html.erb" with:
+      """
+      <h2><%= @widget.name %></h2>
+      """
+    And a file named "app/views/layouts/inventory.html.erb" with:
+      """
+      <%= yield %>
+      """
+    When I run `rspec spec/views`
+    Then the examples should all pass
+
   Scenario: View specs can have description that includes the format and handler
     Given a file named "spec/views/widgets/widget.xml.erb_spec.rb" with:
       """ruby