Using PDF style file from ISA manual

Signed-off-by: Robert Chyla (MIPS) <154632854+mipsrobert@users.noreply.github.com>

docs/Makefile

@@ -21,7 +21,7 @@ OPTIONS := --trace \
            -a compress \
            -a mathematical-format=svg \
            -a pdf-fontsdir=docs-resources/fonts \
-           -a pdf-style=docs-resources/themes/riscv-pdf.yml \
+           -a pdf-style=./riscv-pdf-ISA.yml \
            --failure-level=ERROR
 REQUIRES := --require=asciidoctor-bibtex \
             --require=asciidoctor-diagram \