pnmquantall, ppmquantall: add pages; pnmquant: edit page (#12407)

pages/common/pnmquant.md

@@ -2,6 +2,7 @@
 
 > Quantize the colors in a PNM image into a smaller set.
 > This command is a combination of `pnmcolormap` and `pnmremap` and accepts the union of their options, except `-mapfile`.
+> See also: `pnmquantall`.
 > More information: <https://netpbm.sourceforge.net/doc/pnmquant.html>.
 
 - Generate an image using only `n_colors` or less colors as close as possible to the input image:

pages/common/pnmquantall.md

@@ -0,0 +1,13 @@
+# pnmquantall
+
+> Run `pnmquant` on multiple files at once such that they share a common colormap.
+> See also: `pnmquant`.
+> More information: <https://netpbm.sourceforge.net/doc/pnmquantall.html>.
+
+- Run `pnmquant` on multiple files with the specified parameters, overwriting the original files:
+
+`pnmquantall {{n_colors}} {{path/to/input1.pnm path/to/input2.pnm ...}}`
+
+- Save the quantised images to files named the same as the input files, but with the specified extension appended:
+
+`pnmquantall -ext {{extension}} {{n_colors}} {{path/to/input1.pnm path/to/input2.pnm ...}}`

pages/common/ppmquantall.md

@@ -0,0 +1,8 @@
+# ppmquantall
+
+> This command is superseded by `pnmquantall`.
+> More information: <https://netpbm.sourceforge.net/doc/ppmquantall.html>.
+
+- View documentation for the current command:
+
+`tldr pnmquantall`