Some documentation fixes [ci skip]

activejob/lib/active_job/callbacks.rb

@@ -3,8 +3,8 @@
 module ActiveJob
   # = Active Job Callbacks
   #
-  # Active Job provides hooks during the lifecycle of a job. Callbacks allow you to trigger
-  # logic during the lifecycle of a job. Available callbacks:
+  # Active Job provides hooks during the lifecycle of a job. Callbacks allow you
+  # to trigger logic during the lifecycle of a job. Available callbacks are:
   #
   # * <tt>before_enqueue</tt>
   # * <tt>around_enqueue</tt>

activejob/lib/active_job/gem_version.rb

 module ActiveJob
-  # Returns the version of the currently loaded Active Job as a <tt>Gem::Version</tt>
+  # Returns the version of the currently loaded ActiveJob as a <tt>Gem::Version</tt>
   def self.gem_version
     Gem::Version.new VERSION::STRING
   end

guides/source/4_2_release_notes.md

@@ -289,15 +289,15 @@ Please refer to the [Changelog][action-pack] for detailed changes.
 
 *   The way `assert_select` works has changed; specifically a different library
     is used to interpret css selectors, build the transient DOM that the
-    selectors are applied against, and to extract the data from that DOM.  These
-    changes should only affect edge cases.  Examples:
+    selectors are applied against, and to extract the data from that DOM. These
+    changes should only affect edge cases. Examples:
     *  Values in attribute selectors may need to be quoted if they contain
-       non-alphanumeric characters
-    *  DOMs built from HTML source containing invalid HTML containing improperly
-       nested elements may differ
+       non-alphanumeric characters.
+    *  DOMs built from HTML source containing invalid HTML with improperly
+       nested elements may differ.
     *  If the data selected contains entities, the value selected for comparison
-       used to be raw (example: `AT&T`), and now is evaluated
-       (example: `AT&T`)
+       used to be raw (e.g. `AT&T`), and now is evaluated
+       (e.g. `AT&T`).
 
 
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