Use h4 headings in method docs [ci-skip]

SDoc uses `h3` headings for method signatures, so to preserve heading
hierarchy, method documentation should use `h4`, `h5`, or `h6`.

Author: jonathanhefner

activerecord/lib/active_record/delegated_type.rb

@@ -202,7 +202,7 @@ module DelegatedType
     #   @entry.access_notice_message
     #   @entry.access_notice_message?
     #
-    # === Options
+    # ==== Options
     #
     # The +options+ are passed directly to the +belongs_to+ call, so this is where you declare +dependent+ etc.
     # The following options can be included to specialize the behavior of the delegated type convenience methods.

activerecord/lib/active_record/encryption/encryptable_record.rb

@@ -16,7 +16,7 @@ module EncryptableRecord
       class_methods do
         # Encrypts the +name+ attribute.
         #
-        # === Options
+        # ==== Options
         #
         # * <tt>:key_provider</tt> - A key provider to provide encryption and decryption keys. Defaults to
         #   +ActiveRecord::Encryption.key_provider+.

activerecord/lib/active_record/encryption/encrypted_attribute_type.rb

@@ -15,7 +15,7 @@ class EncryptedAttributeType < ::ActiveModel::Type::Value
       delegate :key_provider, :downcase?, :deterministic?, :previous_schemes, :with_context, :fixed?, to: :scheme
       delegate :accessor, :type, to: :cast_type
 
-      # === Options
+      # ==== Options
       #
       # * <tt>:scheme</tt> - A +Scheme+ with the encryption properties for this attribute.
       # * <tt>:cast_type</tt> - A type that will be used to serialize (before encrypting) and deserialize

activerecord/lib/active_record/relation.rb

@@ -969,7 +969,7 @@ def update_counters(counters)
     # If attribute names are passed, they are updated along with +updated_at+/+updated_on+ attributes.
     # If no time argument is passed, the current time is used as default.
     #
-    # === Examples
+    # ==== Examples
     #
     #   # Touch all records
     #   Person.all.touch_all

activerecord/lib/active_record/secure_token.rb

@@ -30,7 +30,7 @@ module ClassMethods
       # {validates_uniqueness_of}[rdoc-ref:Validations::ClassMethods#validates_uniqueness_of] can.
       # You're encouraged to add a unique index in the database to deal with this even more unlikely scenario.
       #
-      # === Options
+      # ==== Options
       #
       # [:length]
       #   Length of the Secure Random, with a minimum of 24 characters. It will

activerecord/lib/active_record/signed_id.rb

@@ -79,7 +79,7 @@ def find_signed(signed_id, purpose: nil, on_rotation: nil)
       # or has been tampered with. It will also raise an +ActiveRecord::RecordNotFound+ exception if
       # the valid signed id can't find a record.
       #
-      # === Examples
+      # ==== Examples
       #
       #   User.find_signed! "bad data" # => ActiveSupport::MessageVerifier::InvalidSignature
       #

activestorage/lib/active_storage/fixture_set.rb

@@ -50,7 +50,7 @@ class FixtureSet
     # by ActiveSupport::Testing::FileFixtures.file_fixture, and upload
     # the file to the Service
     #
-    # === Examples
+    # ==== Examples
     #
     #   # tests/fixtures/active_storage/blobs.yml
     #   second_thumbnail_blob: <%= ActiveStorage::FixtureSet.blob(

activesupport/lib/active_support/core_ext/date_time/conversions.rb

@@ -11,7 +11,8 @@ class DateTime
   #
   # This method is aliased to <tt>to_formatted_s</tt>.
   #
-  # === Examples
+  # ==== Examples
+  #
   #   datetime = DateTime.civil(2007, 12, 4, 0, 0, 0, 0)   # => Tue, 04 Dec 2007 00:00:00 +0000
   #
   #   datetime.to_fs(:db)            # => "2007-12-04 00:00:00"
@@ -23,7 +24,8 @@ class DateTime
   #   datetime.to_fs(:rfc822)        # => "Tue, 04 Dec 2007 00:00:00 +0000"
   #   datetime.to_fs(:iso8601)       # => "2007-12-04T00:00:00+00:00"
   #
-  # == Adding your own datetime formats to to_fs
+  # ==== Adding your own datetime formats to to_fs
+  #
   # DateTime formats are shared with Time. You can add your own to the
   # Time::DATE_FORMATS hash. Use the format name as the hash key and
   # either a strftime string or Proc instance that takes a time or