[Agents] Fix grammatical error (#27436)

Author: tsriram

src/content/docs/agents/concepts/what-are-agents.mdx

@@ -58,7 +58,7 @@ An agent combines AI's ability to make judgements and call the relevant tools to
 
 ![An agent diagram](~/assets/images/agents/agent-workflow.svg)
 
-An agents can dynamically generate an itinerary and execute on booking reservations, similarly to what you would expect from a travel agent. 
+An agent can dynamically generate an itinerary and execute on booking reservations, similarly to what you would expect from a travel agent. 
 
 ### Three primary components of agent systems: