[docs] LLM prompting guide (#26274)

* llm prompting guide

* updated code examples

* an attempt to fix the code example tests

* set seed in examples

* added a doctest comment

* added einops to the doc_test_job

* string formatting

* string formatting, again

* added the toc to slow_documentation_tests.txt

* minor list fix

* string formatting + pipe renamed

* Apply suggestions from code review
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>

* replaced max_length with max_new_tokens and updated the outputs to match

* minor formatting fix

* removed einops from circleci config

* Apply suggestions from code review
Co-authored-by: Lysandre Debut <hi@lysand.re>

* removed einops and trust_remote_code parameter

---------
Co-authored-by: Patrick von Platen <patrick.v.platen@gmail.com>
Co-authored-by: Lysandre Debut <hi@lysand.re>

docs/source/en/_toctree.yml

@@ -92,6 +92,8 @@
     sections:
     - local: tasks/idefics
       title: Image tasks with IDEFICS
+    - local: tasks/prompting
+      title: LLM prompting guide
     title: Prompting
   title: Task Guides
 - sections:

utils/slow_documentation_tests.txt

 docs/source/en/generation_strategies.md
 docs/source/en/model_doc/ctrl.md
 docs/source/en/task_summary.md
+docs/source/en/tasks/prompting.md
 src/transformers/models/blip_2/modeling_blip_2.py
 src/transformers/models/ctrl/modeling_ctrl.py