Migrate docs from Sphinx to MkDocs (#18145)

Signed-off-by: Harry Mellor <19981378+hmellor@users.noreply.github.com>

docs/mkdocs/hooks/url_schemes.py

@@ -0,0 +1,54 @@
+# SPDX-License-Identifier: Apache-2.0
+import re
+
+from mkdocs.config.defaults import MkDocsConfig
+from mkdocs.structure.files import Files
+from mkdocs.structure.pages import Page
+
+
+def on_page_markdown(markdown: str, *, page: Page, config: MkDocsConfig,
+                     files: Files):
+    gh_icon = ":octicons-mark-github-16:"
+    gh_url = "https://github.com"
+    repo_url = f"{gh_url}/vllm-project/vllm"
+    org_url = f"{gh_url}/orgs/vllm-project"
+    urls = {
+        "issue": f"{repo_url}/issues",
+        "pr": f"{repo_url}/pull",
+        "project": f"{org_url}/projects",
+        "dir": f"{repo_url}/tree/main",
+        "file": f"{repo_url}/blob/main",
+    }
+    titles = {
+        "issue": "Issue #",
+        "pr": "Pull Request #",
+        "project": "Project #",
+        "dir": "",
+        "file": "",
+    }
+
+    scheme = r"gh-(?P<type>.+?):(?P<path>.+?)(#(?P<fragment>.+?))?"
+    inline_link = re.compile(r"\[(?P<title>[^\[]+?)\]\(" + scheme + r"\)")
+    auto_link = re.compile(f"<{scheme}>")
+
+    def replace_inline_link(match: re.Match) -> str:
+        url = f'{urls[match.group("type")]}/{match.group("path")}'
+        if fragment := match.group("fragment"):
+            url += f"#{fragment}"
+
+        return f'[{gh_icon} {match.group("title")}]({url})'
+
+    def replace_auto_link(match: re.Match) -> str:
+        type = match.group("type")
+        path = match.group("path")
+        title = f"{titles[type]}{path}"
+        url = f"{urls[type]}/{path}"
+        if fragment := match.group("fragment"):
+            url += f"#{fragment}"
+
+        return f"[{gh_icon} {title}]({url})"
+
+    markdown = inline_link.sub(replace_inline_link, markdown)
+    markdown = auto_link.sub(replace_auto_link, markdown)
+
+    return markdown