`make clean` leaves now the readmes in place in the source tree.
Also, I have added `module_name_readme` target to `module_name_doc` target as a dependency, so when one calls `module_name_doc` all of the forms are generated, like the .txt and .HTML in the build folder and README in source tree.
This should not be done, the readme is generated as part of the development process, not at compile/install time. The readmes are in the source tree as a documentation for the modules (some of them, although only a few, have also devel-related sections -- should have been more, but nobody got time to focus on documenting inter-module apis).
In other words, the building of the generation has to be done only on demand, for the format that is desired (eg, html, text, pdf, ... or all of them), but not the modules' READMEs, which are actually the text format, but named README in each module folder.