Move pages under tldr, lint run.sh, update docs

tldr/linux/retroarch

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+---
+syntax: markdown
+tags: [tldr, linux]
+source: https://github.com/tldr-pages/tldr.git
+---
+# retroarch
+
+> A frontend for emulators, game engines and media players.
+> The reference implementation of the libretro API.
+> More information: <https://github.com/libretro/RetroArch>.
+
+- Start in the menu mode:
+
+`retroarch`
+
+- Start in full screen mode:
+
+`retroarch --fullscreen`
+
+- List all compiled features:
+
+`retroarch --features`
+
+- Set the path of a configuration file:
+
+`retroarch --config={{path/to/config_file}}`
+
+- Display help:
+
+`retroarch --help`
+
+- Display version:
+
+`retroarch --version`