pio: add page (#5404)

pages/common/pio.md

@@ -0,0 +1,16 @@
+# pio
+
+> Development environment for embedded boards.
+> More information: <https://docs.platformio.org/en/latest/core/userguide/>.
+
+- Show help and list subcommands:
+
+`pio --help`
+
+- Print the version number and exit:
+
+`pio --version`
+
+- Show help for a specific subcommand:
+
+`pio {{subcommand}} --help`