docs: codeblock within a list should be indented

According to the style guide a nested codeblock within a list, which is
the case we are changing here, should be indented, otherwise it will
break the numbering of the list, like it is now. Without this
indentation the numbering looks like: 1., 2., 1.. But that is just
wrong, and should be 1., 2., 3.. The indentation should restore the
right numbering here.

https://github.com/google/styleguide/blob/gh-pages/docguide/style.md#nest-codeblocks-within-lists

BUG=None
R=sdefresne@chromium.org

Review URL: https://codereview.chromium.org/1811613003

Cr-Commit-Position: refs/heads/master@{#381742}
1 file changed