Quote example output strings [ci-skip]

This portrays the return values more accurately and, in some cases,
fixes syntax highlighting when using the upcoming version of SDoc
(thanks to its heuristic for detecting Ruby code vs HTML code).

actionview/lib/action_view/helpers/text_helper.rb

@@ -115,25 +115,25 @@ def truncate(text, options = {}, &block)
       # for <tt>:sanitize</tt> will turn sanitizing off.
       #
       #   highlight('You searched for: rails', 'rails')
-      #   # => You searched for: <mark>rails</mark>
+      #   # => "You searched for: <mark>rails</mark>"
       #
       #   highlight('You searched for: rails', /for|rails/)
-      #   # => You searched <mark>for</mark>: <mark>rails</mark>
+      #   # => "You searched <mark>for</mark>: <mark>rails</mark>"
       #
       #   highlight('You searched for: ruby, rails, dhh', 'actionpack')
-      #   # => You searched for: ruby, rails, dhh
+      #   # => "You searched for: ruby, rails, dhh"
       #
       #   highlight('You searched for: rails', ['for', 'rails'], highlighter: '<em>\1</em>')
-      #   # => You searched <em>for</em>: <em>rails</em>
+      #   # => "You searched <em>for</em>: <em>rails</em>"
       #
       #   highlight('You searched for: rails', 'rails', highlighter: '<a href="search?q=\1">\1</a>')
-      #   # => You searched for: <a href="search?q=rails">rails</a>
+      #   # => "You searched for: <a href=\"search?q=rails\">rails</a>"
       #
       #   highlight('You searched for: rails', 'rails') { |match| link_to(search_path(q: match, match)) }
-      #   # => You searched for: <a href="search?q=rails">rails</a>
+      #   # => "You searched for: <a href=\"search?q=rails\">rails</a>"
       #
       #   highlight('<a href="javascript:alert(\'no!\')">ruby</a> on rails', 'rails', sanitize: false)
-      #   # => <a href="javascript:alert('no!')">ruby</a> on <mark>rails</mark>
+      #   # => "<a href=\"javascript:alert('no!')\">ruby</a> on <mark>rails</mark>"
       def highlight(text, phrases, options = {}, &block)
         text = sanitize(text) if options.fetch(:sanitize, true)
 
@@ -164,22 +164,22 @@ def highlight(text, phrases, options = {}, &block)
       # isn't found, +nil+ is returned.
       #
       #   excerpt('This is an example', 'an', radius: 5)
-      #   # => ...s is an exam...
+      #   # => "...s is an exam..."
       #
       #   excerpt('This is an example', 'is', radius: 5)
-      #   # => This is a...
+      #   # => "This is a..."
       #
       #   excerpt('This is an example', 'is')
-      #   # => This is an example
+      #   # => "This is an example"
       #
       #   excerpt('This next thing is an example', 'ex', radius: 2)
-      #   # => ...next...
+      #   # => "...next..."
       #
       #   excerpt('This is also an example', 'an', radius: 8, omission: '<chop> ')
-      #   # => <chop> is also an example
+      #   # => "<chop> is also an example"
       #
       #   excerpt('This is a very beautiful morning', 'very', separator: ' ', radius: 1)
-      #   # => ...a very beautiful...
+      #   # => "...a very beautiful..."
       def excerpt(text, phrase, options = {})
         return unless text && phrase
 
@@ -222,19 +222,19 @@ def excerpt(text, phrase, options = {})
       # See ActiveSupport::Inflector.pluralize
       #
       #   pluralize(1, 'person')
-      #   # => 1 person
+      #   # => "1 person"
       #
       #   pluralize(2, 'person')
-      #   # => 2 people
+      #   # => "2 people"
       #
       #   pluralize(3, 'person', plural: 'users')
-      #   # => 3 users
+      #   # => "3 users"
       #
       #   pluralize(0, 'person')
-      #   # => 0 people
+      #   # => "0 people"
       #
       #   pluralize(2, 'Person', locale: :de)
-      #   # => 2 Personen
+      #   # => "2 Personen"
       def pluralize(count, singular, plural_arg = nil, plural: plural_arg, locale: I18n.locale)
         word = if count == 1 || count.to_s.match?(/^1(\.0+)?$/)
           singular
@@ -250,21 +250,21 @@ def pluralize(count, singular, plural_arg = nil, plural: plural_arg, locale: I18
       # (which is 80 by default).
       #
       #   word_wrap('Once upon a time')
-      #   # => Once upon a time
+      #   # => "Once upon a time"
       #
       #   word_wrap('Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding a successor to the throne turned out to be more trouble than anyone could have imagined...')
-      #   # => Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding\na successor to the throne turned out to be more trouble than anyone could have\nimagined...
+      #   # => "Once upon a time, in a kingdom called Far Far Away, a king fell ill, and finding\na successor to the throne turned out to be more trouble than anyone could have\nimagined..."
       #
       #   word_wrap('Once upon a time', line_width: 8)
-      #   # => Once\nupon a\ntime
+      #   # => "Once\nupon a\ntime"
       #
       #   word_wrap('Once upon a time', line_width: 1)
-      #   # => Once\nupon\na\ntime
+      #   # => "Once\nupon\na\ntime"
       #
       # You can also specify a custom +break_sequence+ ("\n" by default):
       #
       #   word_wrap('Once upon a time', line_width: 1, break_sequence: "\r\n")
-      #   # => Once\r\nupon\r\na\r\ntime
+      #   # => "Once\r\nupon\r\na\r\ntime"
       def word_wrap(text, line_width: 80, break_sequence: "\n")
         return +"" if text.empty?