further improve readme2index.sh help message

The '-p tool' and '-P optstr' will be passed as leading options on the
-b tool and -a tool command lines, not to the '-o tool' command lines.

Improve help text for readme2index.sh.

The `inc/md2html.cfg` file was updated so that the comment
about options matches the `readme2index.sh` tool usage message.

inc/md2html.cfg

@@ -70,10 +70,10 @@
 #
 #	-p tool		run 'pandoc wrapper tool' (not pandoc path) during HTML phase number 21 (def: use inc/pandoc_wapper.sh)
 #	-p .		skip HTML phase number 21 (def: do nothing during HTML phase number 21)
-#			NOTE: -p tool will be passed as leading options to other tools (-b, -a, -o).
+#			NOTE: The '-p tool' will be passed as leading options on the -b tool and -a tool command lines.
 #	-P optstr	run 'pandoc wrapper tool' with options found in 'optstr' (def: use only the default options)
 #			NOTE: The 'optstr' may not contain a single-quote, nor a double-quote.
-#			NOTE: -P optstr will be passed as leading options to other tools (-b, -a, -o).
+#			NOTE: The '-P optstr' will be passed as leading options on the -b tool and -a tool command lines.
 #
 #	-a tool		run 'after tool' during HTML phase number 20 (def: do not output after pandoc wrapper tool)
 #	-a .		skip HTML phase number 22 (def: do nothing during HTML phase number 22)
@@ -83,8 +83,8 @@
 #	-s token=value	substitute %%token%% with value except in HTML phase numbers 20-29 (def: do not substitute any tokens)
 #			NOTE: The 'token' string may not contain a ; (semicolon), a = (equal), nor a % (percent).
 #			NOTE: The 'value' string may not contain a ; (semicolon).
-#			NOTE: A later -s token=value will override an earlier -s token=value for the same 'token'.
-#			NOTE: Multiple -s token=value are cumulative for the unique set of 'token's.
+#			NOTE: A later '-s token=value' will override an earlier '-s token=value' for the same 'token'.
+#			NOTE: Multiple '-s token=value' are cumulative for the unique set of 'token's.
 #	-S		failure to replace a %%token%% is not an error (def: exit non-zero for non-substituted tokens)
 #
 #	-o tool		Use output tool, 'tool', to generate option lines (def: do not)
@@ -92,7 +92,7 @@
 #			NOTE: -o may only be used in command_options and md2html.cfg cfg_options (getopt phases 0 and 2)
 #	-O tool=optstr	run the 'token replace' named 'tool' with options found in 'optstr' (def: do not add any options)
 #			NOTE: Neither 'tool' nor 'optstr' may not contain an = (equal), a single-quote, nor a double-quote.
-#			NOTE: A later -O tool=optstr will override all earlier -O tool=optstr for the same 'tool'.
+#			NOTE: A later '-O tool=optstr' will override all earlier '-O tool=optstr' for the same 'tool'.
 #			NOTE: -O may only be used in command_options and md2html.cfg cfg_options (getopt phases 0 and 2)
 #
 #	-e string	output 'string', followed by newline, to stderr (def: do not)