opkg: add page (#2035)

pages/linux/opkg.md

@@ -0,0 +1,31 @@
+# opkg
+
+> A lightweight package manager used to install OpenWrt packages.
+
+- Install a package:
+
+`opkg install {{package}}`
+
+- Remove a package:
+
+`opkg remove {{package}}`
+
+- Update the list of available packages:
+
+`opkg update`
+
+- Upgrade all the installed packages:
+
+`opkg upgrade`
+
+- Upgrade one or more specific package(s):
+
+`opkg upgrade {{package(s)}}`
+
+- Display informations for a specific package:
+
+`opkg info {{package}}`
+
+- List all the available packages:
+
+`opkg list`