Optimize TOC for viewing on Github

CONTRIBUTING.adoc

@@ -2,7 +2,6 @@
 # Contributing  to the Spring Framework
 :toc: preamble
 :toclevels: 4
-:docinfo1:
 
 First off, thank you for taking the time to contribute!
 
@@ -123,4 +122,4 @@ Asciidoctor also supports live editing. For more details read
 http://asciidoctor.org/docs/editing-asciidoc-with-live-preview/[Editing AsciiDoc with Live Preview].
 Note that if you choose the
 http://asciidoctor.org/docs/editing-asciidoc-with-live-preview/#using-a-system-monitor[System Monitor]
-option, you can find a Guardfile under `src/docs/asciidoc`.
\ No newline at end of file
+option, you can find a Guardfile under `src/docs/asciidoc`.