tidy-up: miscellaneous

- tool_bname: scope an include.
- `endif` comments.
- Markdown fixes.
- comment tidy-ups.
- whitespace, newlines, indent.

Closes #20309

include/curl/Makefile.am

@@ -25,7 +25,7 @@ pkginclude_HEADERS = \
   curl.h curlver.h easy.h mprintf.h stdcheaders.h multi.h \
   typecheck-gcc.h system.h urlapi.h options.h header.h websockets.h
 
-pkgincludedir= $(includedir)/curl
+pkgincludedir = $(includedir)/curl
 
 CHECKSRC = $(CS_$(V))
 CS_0 = @echo "  RUN     " $@;