doppler: add page (#13345)

Co-authored-by: Sebastiaan Speck <12570668+sebastiaanspeck@users.noreply.github.com>
Co-authored-by: spageektti <git@spageektti.cc>

pages/common/doppler.md

@@ -0,0 +1,29 @@
+# doppler
+
+> Manage environment variables across different environments using Doppler.
+> Some subcommands such as `doppler run` and `doppler secrets` have their own usage documentation.
+> More information: <https://docs.doppler.com/docs/cli>.
+
+- Setup Doppler CLI in the current directory:
+
+`doppler setup`
+
+- Setup Doppler project and config in current directory:
+
+`doppler setup`
+
+- Run a command with secrets injected into the environment:
+
+`doppler run --command {{command}}`
+
+- View your project list:
+
+`doppler projects`
+
+- View your secrets for current project:
+
+`doppler secrets`
+
+- Open doppler dashboard in browser:
+
+`doppler open`