pnmmargin, pnmmontage, pnmnlfilt, pnmnorm, pnmpad, pnmpaste: add pages (#12187)

* pnmmargin, pnmmontage, pnmnlfilt, pnmnorm, pnmpad, pnmpaste: add pages

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Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>
Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

pages/common/pnmpaste.md

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+# pnmpaste
+
+> Paste a PNM image into another PNM image.
+> More information: <https://netpbm.sourceforge.net/doc/pnmpaste.html>.
+
+- Paste a PNM image into another PNM image at the specified coordinates:
+
+`pnmpaste {{x}} {{y}} {{path/to/image1.pnm}} {{path/to/image2.pnm}} > {{path/to/output.pnm}}`
+
+- Paste the image read from `stdin` into the specified image:
+
+`{{command}} | pnmpaste {{x}} {{y}} {{path/to/image.pnm}} > {{path/to/output.pnm}}`
+
+- Combine the overlapping pixels by the specified boolean operation, where white pixels represent `true` while black pixels represent `false`:
+
+`pnmpaste -{{and|nand|or|nor|xor|xnor}} {{x}} {{y}} {{path/to/image1.pnm}} {{path/to/image2.pnm}} > {{path/to/output.pnm}}`