fitstopnm, pamcut, pamdeinterlace, pamdice, pammixinterlace, pamtofits, pamundice, pnmtofits: add pages (#12296)

* fitstopnm, pamcut, pamdeinterlace, pamdice, pammixinterlace, pamtofits, pamundice, pnmtofits: add pages

* Apply suggestions from code review

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* Update pages/common/pamdice.md

* Update pages/common/fitstopnm.md

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* Update pages/common/fitstopnm.md

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* Apply suggestions from code review

Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

* Update pages/common/pamundice.md

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Co-authored-by: Vitor Henrique <87824454+vitorhcl@users.noreply.github.com>

pages/common/pamundice.md

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+# pamundice
+
+> Combine a grid of Netpbm images into one.
+> See also: `pamdice`.
+> More information: <https://netpbm.sourceforge.net/doc/pamundice.html>.
+
+- Combine the images whose names match the `printf`-style filename expression. Assume a grid with a specific size:
+
+`pamundice {{filename_%1d_%1a.ppm}} -across {{grid_width}} -down {{grid_height}} > {{path/to/output.ppm}}`
+
+- Assume that the tiles overlap horizontally and vertically by the specified amount:
+
+`pamundice {{filename_%1d_%1a.ppm}} -across {{x_value}} -down {{y_value}} -hoverlap {{value}} -voverlap {{value}} > {{path/to/output.ppm}}`
+
+- Specify the images to be combined through a text file containing one filename per line:
+
+`pamundice -listfile {{path/to/file.txt}} -across {{x_value}} -down {{y_value}} > {{path/to/output.ppm}}`