The build instructions in the INSTALL documentation does not lead to the
documentation (HTML or man pages) being built.
Here are all the directories I have having followed the instructions:
[pgtest(at)possum pgtest]$ ls postgresql
total 24
drwxrwxr-x 6 pgtest pgtest 4096 Sep 3 16:50 .
drwx------ 9 pgtest pgtest 4096 Sep 3 16:50 ..
drwxrwxr-x 2 pgtest pgtest 4096 Sep 3 16:51 bin
drwxrwxr-x 5 pgtest pgtest 4096 Sep 3 16:50 include
drwxrwxr-x 2 pgtest pgtest 4096 Sep 3 16:51 lib
drwxrwxr-x 5 pgtest pgtest 4096 Sep 3 16:50 pgsql
[pgtest(at)possum pgtest]$