Utp 1.1 - Implemented pdfhref to provide clickable TOC and Index, replaced index scripts with single mkindex.pl

In the "Copying and Moving Files" section the '-F' option is passed to
'ls' to show two files and two directories.  The next command moves one
of the files to a directory and the following example shows a bare 'ls'
but with one of the directories with a trailing '/' character (the
result of the '-F' option).

This patch removes the ambiguity by showing the result when '-F' is
passed to 'ls' by adding the option to the command and showing both
directories with trailing '/' characters.

This ambiguity is also present in the original book available from:
https://www.oreilly.com/openbook/utp/

Extra text was found in the output that matched other uses of the 'ix'
macro.  Replace '129' with '.ix' to fix.

The 'mmt' command is now present in the index.

The value of register Hb controls the heading levels that will have a
line break after the heading.  The addition of " lines" implies that
the value controls the number of blank lines which is not the case per
original AT&T MM documentation:

https://github.com/n-t-roff/DWB3.3/blob/562bb8615116f46077ca03e8561323cc7a89673e/doc/mm/mm.04#L257

Unfortunately, this erroneous text also appears in the original UTP and
confuses the intended use of the register.

The sentence preceeding the description of legal values correctly notes
'1' as the default.  Showing '0' and '1' as 'default' is confusing.  The
available AT&T MM manual confirms the default is '1':

https://github.com/n-t-roff/DWB3.3/blob/562bb8615116f46077ca03e8561323cc7a89673e/doc/mm/mm.04#L282

This extreneous string appears in the original UTP.

The HF example only sets bold for the first four headings while the
explanatory text below states that the first five headings will be in
bold type.  Correct the example to match the text.

This inconsistency is present in the original UTP.

Replace incorrect text with ix macro - changes look reasonable.

Correct ambiguous 'ls' command - Everything looks correct, committed as requested.