Improve documentation for depth argument in SVN buildstep

docs/buildbot.texinfo

@@ -5243,10 +5243,8 @@ build. This is everything that would appear in a @code{svn status}.
 
 @item depth
 (optional): Specify depth argument to achieve sparse checkout.  Only available if slave has Subversion 1.5 or higher.
-empty - updates will not pull in any files or subdirectories not already present.
-files - updates will pull in any files not already present, but not directories.
-immediates - updates willl pull in any files or subdirectories not already present, the new subdirectories will have depth: empty.
-infinity - Updates will pull in any files or subdirectories not already present; the new subdirectories will have depth-infinity. Equivalent to SVN default update behavior.
+
+If set to "empty" updates will not pull in any files or subdirectories not already present. If set to "files", updates will pull in any files not already present, but not directories.  If set to "immediates", updates willl pull in any files or subdirectories not already present, the new subdirectories will have depth: empty.  If set to "infinity", updates will pull in any files or subdirectories not already present; the new subdirectories will have depth-infinity. Infinity is equivalent to SVN default update behavior, without specifying any depth argument.
 
 @end table