pbmtopgm, pbmtoplot, pbmtoppa, pbmtoptx, pbmupc, pgmenhance: add pages (#12224)

pages/common/pbmupc.md

@@ -0,0 +1,12 @@
+# pbmupc
+
+> Generate a PBM image of a Universal Product Code (UPC).
+> More information: <https://netpbm.sourceforge.net/doc/pbmupc.html>.
+
+- Generate a UPC image for the specified product type, manufacturer code, and product code:
+
+`pbmupc {{product_type}} {{manufacturer_code}} {{product_code}} > {{path/to/output.pbm}}`
+
+- Use an alternative style that does not display the checksum:
+
+`pbmupc -s2 {{product_type}} {{manufacturer_code}} {{product_code}} > {{path/to/output.pbm}}`