rage: add page (#11323)

pages/common/rage.md

@@ -0,0 +1,13 @@
+# rage
+
+> A simple, secure and modern file encryption tool (and Rust library) with small explicit keys, no config options, and UNIX-style composability.
+> Rust implementation of `age`.
+> More information: <https://github.com/str4d/rage>.
+
+- Encrypt a file for `user` and save it to `message.age`:
+
+`echo "{{Your secret message}}" | rage --encrypt --recipient {{user}} --output {{path/to/message.age}}`
+
+- Decrypt a file with `identity_file` and save it to `message`:
+
+`rage --decrypt --identity {{path/to/identity_file}} --output {{message}}`