feat: Brought back the docs generator.

docs/cli/envr_completion.md

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+## envr completion
+
+Generate shell completion scripts
+
+### Synopsis
+
+Supported shells:
+
+  nushell
+  bash
+
+```
+envr completion <shell> [flags]
+```
+
+**Arguments:**
+
+* `shell` — Shell to generate completions for
+
+### Options
+
+```
+  -h, --help   show this documentation
+```
+
+### SEE ALSO
+
+* [envr](envr.md)	 - Manage your .env files.