games/freedoom: Include PDF manual

Hello ports@,

Not sure if it is intentional but the freedoom manual is not installed.
It contains information that is likely helpful to players who have not
played before such as lists of hotkeys/weapons/enemies, source port
recommendations, etc. It is however 1.7M in size, is that ok?

Index: Makefile.inc
===================================================================
RCS file: /cvs/ports/games/freedoom/Makefile.inc,v
retrieving revision 1.3
diff -u -p -r1.3 Makefile.inc
--- Makefile.inc 2 Nov 2020 18:39:44 -0000 1.3
+++ Makefile.inc 14 Oct 2021 03:58:55 -0000
@@ -21,7 +21,7 @@ NO_TEST ?= Yes

do-install:
${INSTALL_DATA_DIR} ${PREFIX}/share/doc/${DOOM_PROJECT}
- ${INSTALL_DATA} ${WRKDIST}/*.txt ${WRKDIST}/*.html \
+ ${INSTALL_DATA} ${WRKDIST}/*.txt ${WRKDIST}/*.html ${WRKDIST}/*.pdf \
${PREFIX}/share/doc/${DOOM_PROJECT}
${INSTALL_DATA_DIR} ${PREFIX}/share/doom
${INSTALL_DATA} ${WRKDIST}/*.wad ${PREFIX}/share/doom
Index: freedoom/pkg/PLIST
===================================================================
RCS file: /cvs/ports/games/freedoom/freedoom/pkg/PLIST,v
retrieving revision 1.2
diff -u -p -r1.2 PLIST
--- freedoom/pkg/PLIST 2 Nov 2020 18:39:44 -0000 1.2
+++ freedoom/pkg/PLIST 14 Oct 2021 03:58:55 -0000
@@ -4,6 +4,7 @@ share/doc/freedoom/COPYING.txt
share/doc/freedoom/CREDITS.txt
share/doc/freedoom/NEWS.html
share/doc/freedoom/README.html
+share/doc/freedoom/freedoom-manual.pdf
share/doom/
share/doom/freedoom1.wad
share/doom/freedoom2.wad