[Doc] Add community links (#18657)

Signed-off-by: DarkLight1337 <[email protected]>

Author: DarkLight1337

docs/.nav.yml

@@ -53,4 +53,6 @@ nav:
       preserve_directory_names: true
   - Community:
     - community/*
-    - vLLM Blog: https://blog.vllm.ai
+    - Blog: https://blog.vllm.ai
+    - Forum: https://discuss.vllm.ai
+    - Slack: https://slack.vllm.ai

docs/community/meetups.md

@@ -1,5 +1,5 @@
 ---
-title: vLLM Meetups
+title: Meetups
 ---
 [](){ #meetups }