.pbm, .pgm, .ppm, .pnm extensions added as image files (#989)
.pbm, .pgm, .ppm, .pnm extensions added as image files (#989)

* PPM(Portable Pixel Map) extension added as image

PPM is an image file format. Used to store image as numbers instead of bytes.

* pbm, pgm, pnm extensions added as image files

There is an entire family of image formats called Netpbm. Source [ https://en.wikipedia.org/wiki/Netpbm ]

* pbm extension was added twice. Now its corrected

Co-authored-by: PSEUDO <11415789d536bcef20504c7cfd450f9027b2755b@gmail.ccom>
ycrepeau/vscode-material-icon-theme,PKief/vscode-material-icon-theme,PKief/vscode-material-icon-theme