pbmnoise, pgmhist, pgmkernel, pgmnoise, pgmramp, pgmtexture: add pages; ppmhist: modify page (#12202)

pages/common/pbmnoise.md

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+# pbmnoise
+
+> Generate white noise.
+> More information: <https://netpbm.sourceforge.net/doc/pbmnoise.html>.
+
+- Generate a PGM image containing white noise:
+
+`pbmnoise {{width}} {{height}} > {{path/to/output.pbm}}`
+
+- Specify the seed for the pseudo-random number generator:
+
+`pbmnoise {{width}} {{height}} -randomseed {{value}} > {{path/to/output.pbm}}`
+
+- Specify the desired rate of white to black pixels:
+
+`pbmnoise {{width}} {{height}} -ratio {{1/3}} > {{path/to/output.pbm}}`