Add documentation for gt, the Gitea CLI (#603)

Adds a CLI product for gt (https://gitea.com/gitea/cli), set up like the runner, with short guides for installation, logging in, CI and scripting. Each command's details stay in gt <command> --help. Until the first release, the docs are served at /cli/; make cut-version PRODUCT=cli VERSION=0.1 adds the release series.

Closes https://gitea.com/gitea/cli/issues/16

<!-- cloudflare-preview --> Preview: https://pr-603.docs-gitea-com.pages.dev

---------

Co-authored-by: silverwind <[email protected]>
Reviewed-on: https://gitea.com/gitea/docs/pulls/603
Reviewed-by: Lunny Xiao <[email protected]>
Reviewed-by: silverwind <[email protected]>

cloudflare/_redirects

@@ -1,11 +1,13 @@
 # Redirects for legacy URLs and routes the site no longer serves directly.
 
-# The api reference and the runner docs are separate products, published in
-# english only, so they have no localized copy.
+# The api reference, the runner and the cli docs are separate products,
+# published in english only, so they have no localized copy.
 /zh-cn/api/* /api/:splat 301
 /zh-tw/api/* /api/:splat 301
 /zh-cn/runner/* /runner/:splat 301
 /zh-tw/runner/* /runner/:splat 301
+/zh-cn/cli/* /cli/:splat 301
+/zh-tw/cli/* /cli/:splat 301
 
 # The version served at the root of a product is also reachable under its
 # number, which is what the release notes and old links use.

cloudflare/docsearch-crawler.json

@@ -7,6 +7,7 @@
     "https://docs.gitea.com/zh-cn/",
     "https://docs.gitea.com/zh-tw/",
     "https://docs.gitea.com/runner/",
+    "https://docs.gitea.com/cli/",
     "https://docs.gitea.com/api/",
     "https://docs.gitea.com/enterprise/"
   ],
@@ -15,7 +16,8 @@
     "https://docs.gitea.com/1.2*/**",
     "https://docs.gitea.com/*/1.2*/**",
     "https://docs.gitea.com/api/1.2*/**",
-    "https://docs.gitea.com/runner/[0-9]/**"
+    "https://docs.gitea.com/runner/[0-9]/**",
+    "https://docs.gitea.com/cli/[0-9]*/**"
   ],
   "selectors": {
     "lvl0": { "selector": "//nav[contains(@aria-labelledby,'starlight__sidebar')]//a[@aria-current='page']/ancestor::details//summary//span", "type": "xpath", "global": true, "default_value": "Documentation" },