Update cheatsheets

tldr/linux/steamos-devmode

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+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# steamos-devmode
+
+> Enable SteamOS developer mode.
+> Note: Developer mode disables read-only protections and initializes the package manager.
+> More information: <https://gitlab.com/users/evlaV/projects>.
+
+- Enable developer mode:
+
+`sudo steamos-devmode enable`
+
+- Enable developer mode without confirmation prompt:
+
+`sudo steamos-devmode enable --no-prompt`
+
+- Check if developer mode is currently enabled:
+
+`sudo steamos-devmode status`