[Docs] Fix broken links and syntax issues (#28918)

* Fix model documentation links in attention.md

* Fix external link syntax

* Fix target anchor names of section links

* Fix copyright statement comments

* Fix documentation headings

docs/source/en/tasks/idefics.md

@@ -36,7 +36,7 @@ being a large model means it requires significant computational resources and in
 this approach suits your use case better than fine-tuning specialized models for each individual task. 
 
 In this guide, you'll learn how to: 
-- [Load IDEFICS](#loading-the-model) and [load the quantized version of the model](#loading-the-quantized-version-of-the-model)
+- [Load IDEFICS](#loading-the-model) and [load the quantized version of the model](#quantized-model)
 - Use IDEFICS for: 
   - [Image captioning](#image-captioning)
   - [Prompted image captioning](#prompted-image-captioning)

docs/source/en/tasks/prompting.md

@@ -35,7 +35,7 @@ practices that help to achieve optimal results more consistently.
 This guide covers the prompt engineering best practices to help you craft better LLM prompts and solve various NLP tasks. 
 You'll learn:
 
-- [Basics of prompting](#basic-prompts)
+- [Basics of prompting](#basics-of-prompting)
 - [Best practices of LLM prompting](#best-practices-of-llm-prompting)
 - [Advanced prompting techniques: few-shot prompting and chain-of-thought](#advanced-prompting-techniques)
 - [When to fine-tune instead of prompting](#prompting-vs-fine-tuning)