help center: Remove outdated intro from index page.

templates/zerver/help/index.md

@@ -1,16 +1,5 @@
 # Zulip help center
 
-Zulip is a group chat app. Its most distinctive characteristic is that
-conversation within an organization is divided into “**streams**”
-and further subdivided into “**topics**”, so that
-much finer-grained conversations are possible than with IRC or other
-chat tools.
-
-Most people use Zulip on the Web. There are also mobile apps for
-Android/iOS, and desktop apps for Mac/Linux/Windows, which can be
-downloaded [here](https://zulip.com/apps/).
-
-One Zulip account, associated with a particular company, project, or team,
-is known as an **organization**.
+Welcome to the [Zulip](/) help center!
 
 {!sidebar_index.md!}

zerver/tests/test_middleware.py

@@ -124,12 +124,7 @@ class OpenGraphTest(ZulipTestCase):
         self.check_title_and_description(
             "/help/",
             "Zulip Help Center",
-            [
-                (
-                    "Zulip is a group chat app. Its most distinctive characteristic is that "
-                    "conversation within an organization is divided into “streams” and further "
-                )
-            ],
+            [("Welcome to the Zulip")],
             [],
         )