* doc/ref/autoconf.texi (Using Autoconf Macros): Switch example to use
PKG_CHECK_MODULES.
* doc/ref/libguile-linking.texi (A Sample Guile Main Program): Likewise,
and change from configure.in to configure.ac, and recommend
autoreconf.
* doc/ref/api-options.texi (Build Config):
* doc/ref/libguile-linking.texi (Linking Programs With Guile):
(A Sample Guile Main Program):
* doc/ref/libguile-smobs.texi (The Complete Example): Use pkg-config in
the examples instead of guile-config.
* doc/ref/intro.texi (Linking Guile into Programs):
* doc/ref/libguile-linking.texi (A Sample Guile Main Program): Update
examples of how to link with guile.