Improve OpenBB tool template to clarify the input

The previous version was sometimes just giving the ticker, and nothing
about the data description (e.g., historical price).

Author: Dedalo314

.env.template

@@ -25,7 +25,7 @@ LLM_TEMPERATURE=0
 LLM_MAX_TOKENS=512
 
 # Description of the OpenBB chat tool
-OPENBBCHAT_TOOL_DESCRIPTION="useful to get historical pricing tabular data. Input should be the concrete data to retrieve."
+OPENBBCHAT_TOOL_DESCRIPTION="useful to get historical pricing tabular data. Input should be a description of the data to retrieve and the dates in ISO format."
 WORLD_KNOWLEDGE_TOOL_DESCRIPTION="useful to solve complex or incomplete financial questions and to search on the Internet current events, news and concrete financial datapoints. Input must be an extended description of the information to search."
 AUTOMULTISTEPQUERYENGINE_INDEX_SUMMARY="useful to search information on the Internet. Input must be an extended description of the information to search."