docs: use realistic client capability (modelcontextprotocol#1320)

The doc mentions that clients can send capability to call tools, is
confusing. The server can send that it may handle tools but the client
does not have to mention that it can perform this ability.

Elicitation is a capability that's listed in the schema.

Co-authored-by: eulegang <[email protected]>

Author: eulegang

docs/docs/learn/architecture.mdx

@@ -162,7 +162,7 @@ MCP begins with lifecycle management through a capability negotiation handshake.
     "params": {
       "protocolVersion": "2025-06-18",
       "capabilities": {
-        "tools": {}
+        "elicitation": {}
       },
       "clientInfo": {
         "name": "example-client",
@@ -206,7 +206,7 @@ In this example, the capability negotiation demonstrates how MCP primitives are
 
 **Client Capabilities**:
 
-- `"tools": {}` - The client declares it can work with the tools primitive (can call `tools/list` and `tools/call` methods)
+- `"elicitation": {}` - The client declares it can work with user interaction requests (can receive `elicitation/create` method calls)
 
 **Server Capabilities**: