Polish contribution

Closes gh-1509

Author: snicoll

CONTRIBUTING-DOCUMENTATION.adoc

@@ -1,14 +1,17 @@
 = How to contribute to the reference manual
 
-The Spring Framework reference manual uses http://asciidoctor.org/[asciidoctor].
-This document describes how to contribute documentation updates.
+The Spring Framework reference manual uses http://asciidoctor.org/[asciidoctor]. This
+document describes how to contribute documentation updates.
 
 == Building with Gradle
 
-You can build the documentation using Gradle using the `asciidoctor` task. For example, from
-the project root execute the following command:
+You can build the documentation using Gradle using the `asciidoctor` task. For example,
+from the project root execute the following command:
 
+[indent=0]
+----
 	./gradlew asciidoctor
+----
 
 The generated reference manual will then be available at `build/asciidoc/html5/index.html`.
 
@@ -22,9 +25,9 @@ http://asciidoctor.org/docs/editing-asciidoc-with-live-preview/[Editing AsciiDoc
 with Live Preview] document. Once you have done that, there are additional gems to
 install to make it work (assuming that you are using http://livereload.com/[LiveReload]):
 
-[source]
+[indent=0]
 ----
-gem install guard-rspec guard-livereload
+	gem install guard-rspec guard-livereload
 ----
 
 When running `guard start` within the `src/asciidoc/` folder, any changes to the
@@ -33,13 +36,13 @@ When running `guard start` within the `src/asciidoc/` folder, any changes to the
 
 == Troubleshooting
 
-* If you are using LiveReload, make sure to select _Allow access to file
-URLs_ in the LiveEdit plugin options of your browser.
-* The icon used to enable _LiveReload_ can be a bit confusing. The dot is empty
-when it is disabled and full when the plugin is active. Make sure to enable it
-on the tab displaying the `index.html` file.
-* Ensure you are _not_ running `guard start` at all as two instances could not run
-at the same time. To exit a current session in a clean way, type `e` in the shell.
+* If you are using LiveReload, make sure to select _Allow access to file URLs_ in the
+LiveEdit plugin options of your browser.
+* The icon used to enable _LiveReload_ can be a bit confusing. The dot is empty when it
+is disabled and full when the plugin is active. Make sure to enable it on the tab
+displaying the `index.html` file.
+* Ensure you are _not_ running `guard start` at all as two instances could not run at the
+same time. To exit a current session in a clean way, type `e` in the shell.
 
 == Documentation Notes