Miscellaneous UI updates (#6094)

### What problem does this PR solve?

#6049 

### Type of change

- [x] Documentation Update
- [x] Other (please describe): UI updates

docs/guides/agent/agent_component_reference/begin.mdx

@@ -31,6 +31,10 @@ An opening greeting is the agent's first message to the user. It can be a welcom
 
 You can set global variables within the **Begin** component, which can be either required or optional. Once established, users will need to provide values for these variables when interacting or chatting with the agent. Click **+ Add variable** to add a global variable, each with the following attributes:
 
+:::caution WARNING
+If your agent's **Begin** component takes a variable, you *cannot* embed it into a webpage.
+:::
+
 - **Key**: *Required*  
   The unique variable name.
 - **Name**: *Required*  

docs/guides/agent/embed_agent_into_webpage.md

@@ -8,7 +8,7 @@ slug: /embed_agent_into_webpage
 You can use iframe to embed an agent into a third-party webpage.
 
 :::caution WARNING
-If your agent's **Begin** component takes a key of **file** type (a **file** type variable), you *cannot* embed it into a webpage.
+If your agent's **Begin** component takes a variable, you *cannot* embed it into a webpage.
 :::
 
 1. Before proceeding, you must [acquire an API key](../models/llm_api_key_setup.md); otherwise, an error message would appear.