pginstaller - web: Change screenshots to 8.1.

Log Message:
-----------
Change screenshots to 8.1.
Update instructions for 8.1. Oops.

Modified Files:
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web:
index.html (r1.7 -> r1.8)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/index.html.diff?r1=1.7&r2=1.8)
pginst0.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst0.png.diff?r1=1.1&r2=1.2)
pginst1.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst1.png.diff?r1=1.1&r2=1.2)
pginst10.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst10.png.diff?r1=1.1&r2=1.2)
pginst11.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst11.png.diff?r1=1.1&r2=1.2)
pginst2.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst2.png.diff?r1=1.1&r2=1.2)
pginst3.png (r1.2 -> r1.3)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst3.png.diff?r1=1.2&r2=1.3)
pginst4.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst4.png.diff?r1=1.1&r2=1.2)
pginst5.png (r1.2 -> r1.3)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst5.png.diff?r1=1.2&r2=1.3)
pginst6.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst6.png.diff?r1=1.1&r2=1.2)
pginst7.png (r1.2 -> r1.3)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst7.png.diff?r1=1.2&r2=1.3)
pginst8.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst8.png.diff?r1=1.1&r2=1.2)
pginst9.png (r1.1 -> r1.2)
(http://cvs.pgfoundry.org/cgi-bin/cvsweb.cgi/pginstaller/web/pginst9.png.diff?r1=1.1&r2=1.2)