The most important part of CLISP documentation, "impnotes.html" is not installed in any version of CLISP ebuild. This file describes most deviations from ANSI Common Lisp Standard and most extensions implemented in CLISP. The file is generated from an XML source, but the HTML version is already in the distribution, so to my mind, it's only a matter of adding a proper "dodoc" to the ebuild Reproducible: Always Steps to Reproduce:
fixed in the latest ebuild