feat: update readme playstation

Update Playstation to PlayStation as "Playstation" is not a known user agent.

readme.md

@@ -81,7 +81,7 @@ AIX, Amiga OS, Android, Arch, Bada, BeOS, BlackBerry, CentOS, Chromium OS,
 Contiki, Fedora, Firefox OS, FreeBSD, Debian, DragonFly, Fuchsia, Gentoo, GNU,
 Haiku, Hurd, iOS, Joli, KaiOS, Linpus, Linux, Mac OS, Mageia, Mandriva, MeeGo,
 Minix, Mint, Morph OS, NetBSD, Nintendo, OpenBSD, OpenVMS, OS/2, Palm, PC-BSD,
-PCLinuxOS, Plan9, Playstation, QNX, RedHat, RIM Tablet OS, RISC OS, Sailfish,
+PCLinuxOS, Plan9, PlayStation, QNX, RedHat, RIM Tablet OS, RISC OS, Sailfish,
 Series40, Slackware, Solaris, SUSE, Symbian, Tizen, Ubuntu, Unix, VectorLinux,
 WebOS, Windows [Phone/Mobile], Zenwalk, ...