The contents of this file was removed while the build of Pine for an ALT's GNU/Linux distribution. Nevertherless you can read all the information that was here in one of the files in tech-notes/ (either in plain text or HTML format). In my view, several files are even more handy then one huge file. The tech-notes have been included into a separate "doc" package and if installed, they will be placed into a separate dir in /usr/share/doc/.