pnmtopalm: add page; palmtopnm: modify page (#11751)

* palmtopnm, pnmtopalm: add pages

* move to common

* fix typos

* Update pages/common/palmtopnm.md

Co-authored-by: Sebastiaan Speck <12570668+sebastiaanspeck@users.noreply.github.com>

* Update pages/common/pnmtopalm.md

Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

---------

Co-authored-by: Sebastiaan Speck <12570668+sebastiaanspeck@users.noreply.github.com>
Co-authored-by: K.B.Dharun Krishna <kbdharunkrishna@gmail.com>

pages/common/pnmtopalm.md

@@ -0,0 +1,24 @@
+# pnmtopalm
+
+> Convert a PNM image to a Palm bitmap.
+> More information: <https://netpbm.sourceforge.net/doc/pnmtopalm.html>.
+
+- Convert a PNM image to a Palm bitmap:
+
+`pnmtopalm {{path/to/file.pnm}} > {{path/to/file.palm}}`
+
+- Specify the color depth of the resulting bitmap:
+
+`pnmtopalm -depth {{1|2|4|8|16}} {{path/to/file.pnm}} > {{path/to/file.palm}}`
+
+- Choose a compression method for the resulting bitmap:
+
+`pnmtopalm -{{scanline_compression|rle_compression|packbits_compression}} {{path/to/file.pnm}} > {{path/to/file.palm}}`
+
+- Build a custom colormap and include it in the resulting bitmap:
+
+`pnmtopalm -colormap {{path/to/file.pnm}} > {{path/to/file.palm}}`
+
+- Specify the bitmap's density:
+
+`pnmtopalm -density {{72|108|144|216|288}} {{path/to/file.pnm}} > {{path/to/file.palm}}`