autotools still mentioned in the docs

markdown/contribute/index.md
233:the gst-plugins-bad module, including `configure.ac`, the various `Makefile.am`

markdown/plugin-development/basics/boiler.md
99:Now one needs to adjust the `Makefile.am` to use the new filenames and

markdown/additional/design/orc-integration.md
38:The following lines are added near the top of Makefile.am for plugins
119:If you create another .orc file, please add it to tests/orc/Makefile.am.

markdown/frequently-asked-questions/developing.md
54:2. [`gst-uninstalled`][gst-uninstalled] is our traditional autotools