docs: Add section on handling temporary pre-release versions in livecheck

docs/Brew-Livecheck.md

@@ -261,6 +261,50 @@ end
 
 You can find more information on the response JSON from this API endpoint in the related [GitHub REST API documentation](https://docs.github.com/en/rest/releases/releases?apiVersion=latest#list-releases).
 
+### Handling Temporary Pre-Release Versions from GitHub
+
+Some packages temporarily need to use pre-release versions (e.g., beta, RC) following the [documented exception](https://docs.brew.sh/Acceptable-Casks#but-there-is-no-stable-version) for software without a stable release. This requires a special livecheck configuration that differs from the standard GitHub strategies.
+
+Unlike the regular `GithubReleases` example above (which filters out pre-release versions), this configuration specifically includes and matches version strings with pre-release suffixes:
+
+```ruby
+# TODO: Update this to use the `GithubLatest` strategy (without a regex or
+# `strategy` block) when a stable version becomes available.
+livecheck do
+  url :url
+  regex(/^v?(\d+(?:\.\d+)+.+)$/i)  # Note the .+ to match version suffixes
+  strategy :github_releases do |json, regex|
+    json.filter_map do |release|
+      next if release["draft"]
+      # Intentionally NOT filtering pre-releases with: next if release["prerelease"]
+
+      match = release["tag_name"]&.match(regex)
+      next if match.blank?
+
+      match[1]
+    end
+  end
+end
+```
+
+This specialized configuration:
+
+1. Uses `url :url` to reference the primary URL, which the GitHub strategies will convert to the appropriate API endpoint
+2. Includes a regex that **specifically allows version strings with suffixes** (like `-beta`, `-rc.1`)
+3. Uses a `strategy` block that:
+   - Filters out draft releases but keeps pre-releases
+   - Matches the tag name against the regex
+   - Returns the captured version string including any pre-release suffixes
+
+**Important:** This configuration is intended to be temporary. When a stable version becomes available, the formula or cask should be updated to use a simpler approach:
+
+```ruby
+livecheck do
+  url :url
+  strategy :github_latest
+end
+```
+
 #### `Crate` `strategy` block
 
 A `strategy` block for `Crate` receives parsed JSON data from the registry API's `versions` endpoint and either the provided or default strategy regex. The strategy uses the following logic by default, so this `strategy` block may be a good starting point for a modified approach: