pamfunc, ppmchange, ppmcie, ppmcolormask, ppmdim, ppmdist, ppmfade, ppmforge: add pages (#11449)

Co-authored-by: Lena <126529524+acuteenvy@users.noreply.github.com>

pages/common/ppmforge.md

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+# ppmforge
+
+> Generate fractals resembling clouds, planets and starry skies.
+> More information: <https://netpbm.sourceforge.net/doc/ppmforge.html>.
+
+- Generate an image of a planet:
+
+`ppmforge > {{path/to/image.ppm}}`
+
+- Generate an image of clouds or the night sky:
+
+`ppmforge -{{night|clouds}} > {{path/to/image.ppm}}`
+
+- Use a custom mesh size and dimension for fractal generation and specify the dimensions of the output:
+
+`ppmforge -mesh {{512}} -dimension {{2.5}} -xsize {{1000}} -ysize {{1000}} > {{path/to/image.ppm}}`
+
+- Control the tilt and the angle from which the generated planet is illuminated:
+
+`ppmforge -tilt {{-15}} -hour {{12}} > {{path/to/image.ppm}}`