feat: generate the gt command reference from gitea/cli

update_cli_docs.sh runs gt's own generator and lays the pages out for the
site: one directory per command group, front matter, titles, sidebar
order, fenced help text and rewritten links. --released succeeds while no
series is documented. A weekly workflow proposes updates like the runner's.

Signed-off-by: bircni <[email protected]>

cli-docs/reference/help/index.md

@@ -0,0 +1,14 @@
+---
+sidebar_position: 30
+description: "Guides built into gt, read with gt help <topic>."
+---
+
+# Help topics
+
+<!-- Generated by update_cli_docs.sh from the gitea/cli sources, do not edit. -->
+
+Guides built into gt, read with `gt help <topic>`:
+
+- [gt help environment](environment.md): Environment variables and global flags
+- [gt help exit-codes](exit-codes.md): Exit codes used by gt
+- [gt help formatting](formatting.md): JSON output with --json and --jq