eqn, grap, groff, pic, tbl, troff: add page (#6868)

pages/common/pic.md

@@ -0,0 +1,13 @@
+# pic
+
+> Picture preprocessor for the groff (GNU Troff) document formatting system.
+> See also `groff` and `troff`.
+> More information: <https://manned.org/pic>.
+
+- Process input with pictures, saving the output for future typesetting with groff to PostScript:
+
+`pic {{path/to/input.pic}} > {{path/to/output.roff}}`
+
+- Typeset input with pictures to PDF using the [me] macro package:
+
+`pic -T {{pdf}} {{path/to/input.pic}} | groff -{{me}} -T {{pdf}} > {{path/to/output.pdf}}`