docs: Improve examples page (#5442)

* Fix VoiceAgent to use run_manager instead of job_manager

VoiceAgent.__init__() was incorrectly using job_manager parameter
when ToolExecutionManager expects run_manager. This was causing
the error: "VoiceAgent.__init__() got an unexpected keyword
argument 'run_manager'".

Changes:
- Update VoiceAgent to accept and use run_manager instead of job_manager
- Update VoiceSleeptimeAgent to accept run_manager parameter
- Update imports to use RunManager instead of JobManager
- Pass run_manager to ToolExecutionManager in VoiceAgent._execute_tool

* docs: Add new examples to documentation

- Introduced "Your First Agent" example to guide users in creating a Letta agent and understanding its memory capabilities.
- Added "Attaching and Detaching Memory Blocks" example to demonstrate dynamic memory management for agents.
- Updated navigation in docs.yml to include links to the new examples.

These additions enhance the learning resources available for users working with Letta agents.

letta/agents/voice_sleeptime_agent.py

@@ -14,9 +14,9 @@ from letta.schemas.tool_rule import ChildToolRule, ContinueToolRule, InitToolRul
 from letta.schemas.user import User
 from letta.services.agent_manager import AgentManager
 from letta.services.block_manager import BlockManager
-from letta.services.job_manager import JobManager
 from letta.services.message_manager import MessageManager
 from letta.services.passage_manager import PassageManager
+from letta.services.run_manager import RunManager
 from letta.services.summarizer.enums import SummarizationMode
 from letta.services.summarizer.summarizer import Summarizer
 from letta.types import JsonDict
@@ -34,7 +34,7 @@ class VoiceSleeptimeAgent(LettaAgent):
         message_manager: MessageManager,
         agent_manager: AgentManager,
         block_manager: BlockManager,
-        job_manager: JobManager,
+        run_manager: RunManager,
         passage_manager: PassageManager,
         target_block_label: str,
         actor: User,
@@ -44,7 +44,7 @@ class VoiceSleeptimeAgent(LettaAgent):
             message_manager=message_manager,
             agent_manager=agent_manager,
             block_manager=block_manager,
-            job_manager=job_manager,
+            job_manager=run_manager,
             passage_manager=passage_manager,
             actor=actor,
         )