Having a system without rst2html:

``` checking for rst2html... no checking for rst2html.py... no configure: error: Documentation enabled but rst2html not found. You can explicitly disable building of the HTML manual with --disable-html-docs, but you then may not have a local copy of the HTML manual. ```

but ./configure -help tells, it's auto:

``` --enable-html-docs generate HTML documentation using rst2html [default=auto] --enable-pdf-docs generate PDF documentation using rst2pdf [default=auto] --enable-api-docs generate API documentation using Doxygen [default=auto] ```