Add reverse prompting example

[davidrpugh]

llama-cli supports reverse prompting. Reverse prompts are a powerful way to create a chat-like experience with your model by pausing the text generation when specific text strings are encountered using the --reverse-prompt option.

• -r PROMPT, --reverse-prompt PROMPT: Specify one or multiple reverse prompts to pause text generation and switch to interactive mode. For example, -r "User:" can be used to jump back into the conversation whenever it's the user's turn to speak. This helps create a more interactive and conversational experience.

The --in-prefix flag is used to add a prefix to your input, primarily, this is used to insert a space after the reverse prompt. Here's an example of how to use the --in-prefix flag in conjunction with the --reverse-prompt flag:

llama-cli -r "User:" --in-prefix " "

The --in-suffix flag is used to add a suffix after your input. This is useful for adding an "Assistant:" prompt after the user's input. It's added after the new-line character (\n) that's automatically added to the end of the user's input. Here's an example of how to use the --in-suffix flag in conjunction with the --reverse-prompt flag:

./llama-cli -r "User:" --in-prefix " " --in-suffix "Assistant:"

When --in-prefix or --in-suffix options are enabled the chat template ( --chat-template ) is disabled.

Need a good example use case for this functionality.