do not render relative links in help pages

this simplifies the setup a lot, and avoids weird looking `./file.md`
links showing up.

it also does not show regular URLs any more. currently the command
reference only has few of them, and not showing them in the offline
documentation is hopefully not a big deal.

instead of building more special-case solutions, clumsily preprocessing
the input, or issuing verbal rules on dealing with URLs, should better
be solved sustainably by not rendering relative links in `lowdown`:

kristapsdz/lowdown#105

doc/manual/generate-manpage.nix

@@ -1,4 +1,4 @@
-{ command, renderLinks ? false }:
+{ command }:
 
 with builtins;
 with import ./utils.nix;
@@ -21,9 +21,7 @@ let
            listCommands = cmds:
              concatStrings (map (name:
                "* "
-               + (if renderLinks
-                  then "[`${command} ${name}`](./${appendName filename name}.md)"
-                  else "`${command} ${name}`")
+               + "[`${command} ${name}`](./${appendName filename name}.md)"
                + " - ${cmds.${name}.description}\n")
                (attrNames cmds));
          in

doc/manual/local.mk

@@ -50,7 +50,7 @@ $(d)/src/SUMMARY.md: $(d)/src/SUMMARY.md.in $(d)/src/command-ref/new-cli
 
 $(d)/src/command-ref/new-cli: $(d)/nix.json $(d)/generate-manpage.nix $(bindir)/nix
 	@rm -rf $@
-	$(trace-gen) $(nix-eval) --write-to $@ --expr 'import doc/manual/generate-manpage.nix { command = builtins.readFile $<; renderLinks = true; }'
+	$(trace-gen) $(nix-eval) --write-to $@ --expr 'import doc/manual/generate-manpage.nix { command = builtins.readFile $<; }'
 
 $(d)/src/command-ref/conf-file.md: $(d)/conf-file.json $(d)/generate-options.nix $(d)/src/command-ref/conf-file-prefix.md $(bindir)/nix
 	@cat doc/manual/src/command-ref/conf-file-prefix.md > $@.tmp
@@ -96,7 +96,7 @@ doc/manual/generated/man1/nix3-manpages: $(d)/src/command-ref/new-cli
 	  if [[ $$name = SUMMARY ]]; then continue; fi; \
 	  printf "Title: %s\n\n" "$$name" > $$tmpFile; \
 	  cat $$i >> $$tmpFile; \
-	  lowdown -sT man -M section=1 $$tmpFile -o $(DESTDIR)$$(dirname $@)/$$name.1; \
+	  lowdown -sT man --nroff-nolinks -M section=1 $$tmpFile -o $(DESTDIR)$$(dirname $@)/$$name.1; \
 	  rm $$tmpFile; \
 	done
 	@touch $@

src/libcmd/markdown.cc

@@ -18,7 +18,7 @@ std::string renderMarkdownToTerminal(std::string_view markdown)
         .hmargin = 0,
         .vmargin = 0,
         .feat = LOWDOWN_COMMONMARK | LOWDOWN_FENCED | LOWDOWN_DEFLIST | LOWDOWN_TABLES,
-        .oflags = 0,
+        .oflags = LOWDOWN_TERM_NOLINK,
     };
 
     auto doc = lowdown_doc_new(&opts);