Manual: be more agnostic w.r.t. version control system used.

Manual: be more agnostic w.r.t. version control system used.

* doc/automake.texi (Basics of Distribution): Also refer to `.svn'
directories as a type of probably-unwanted files that are copied
regardless when adding directories to EXTRA_DIST.
(The dist Hook): Show a dist-hook example which removes Subversion
`.svn' private directories from distdir, rather than CVS private
directories.
(missing and AM_MAINTAINER_MODE): Try to be more agnostic w.r.t.
the version control system used.