docs: update function-calling.md w/ template override needed by functionary-small-v3.2

[ochafik]

Fixes misleading command in doc revealed by #12213 (cc/ @edmcman): bartowski/functionary-small-v3.2-GGUF needs a template override.

Also, now using predownloaded templates under model/templates (used by test_tool_call.py) to simplify commands, and add extra blurb about the python script to get more templates.

[pepijndevos]

Is there any plan to automatically provide the right templates if they are shipped with llama.cpp anyway? I might just apply them in my wrapper but just checking.

[ochafik]

Is there any plan to automatically provide the right templates if they are shipped with llama.cpp anyway? I might just apply them in my wrapper but just checking.

I think there are multiple options here:

• (Ideally) Reach out to each maintainer of a GGUF with bad or out of date templates, and have them fix them.
• Detect and explode on "bad" templates (maybe advising on using the GGUF editor to fix the template?)
• Add a simple way to specify which HF repo to pull a template from (-hft / --hf-template flag? add the original HF repo as a key in the GGUF?)
• Bundle a collection of "good" templates and use a mix of predicates on the model metadata to pick the right template (ignoring the template built into the GGUF)

I reckon we could add a flag that switches between the behaviours of the 3 last bullets

cc/ @ngxson @ggerganov WDYT?

[ngxson]

If the number of known broken templates are rare (i.e. the case of functionary, it is one of the first model to support function call so it was quite messy), then I don't want to spend too much effort fixing this.

The easiest solution is to simply bundle a collection of good templates as you said on your last point. I believe we will end up with a list of around 10 of them. Newer models should not need this, because they should already have a good built-in template.