Update doc linting tools and rules

What does this merge request do and why?

This updates doc linting tools and rules (see guide).

I have also fixed new markdownlint-cli2 errors.

❯ make lint-doc                                                                                                                     
Running markdownlint-cli2...                                                                                                        
markdownlint-cli2 v0.19.0 (markdownlint v0.39.0)                                                                                    
Finding: doc/**/*.md README.md                                                                                                      
Linting: 38 file(s)                                                                                                                 
Summary: 6 error(s)                                                                                                                 
doc/eval_scenarios/duo_chat/docs.md:101:58 error MD059/descriptive-link-text Link text should be descriptive [Context: "[here]"]    
doc/eval_scenarios/duo_chat/follow_up_question_eval.md:90:46 error MD059/descriptive-link-text Link text should be descriptive [Cont
ext: "[here]"]                                                    
doc/eval_scenarios/duo_workflow/swe_inspect.md:46:30 error MD059/descriptive-link-text Link text should be descriptive [Context: "[l
ink]"]                                                            
doc/evaluators/index.md:81:62 error MD059/descriptive-link-text Link text should be descriptive [Context: "[here]"]                 
doc/evaluators/index.md:97:62 error MD059/descriptive-link-text Link text should be descriptive [Context: "[here]"]                 
doc/evaluators/pairwise.md:7:2 error MD059/descriptive-link-text Link text should be descriptive [Context: "[here]"]                
make: *** [Makefile:72: markdownlint] Error 1    

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Merge request checklist

• I've ran the affected pipeline(s) to validate that nothing is broken.
• Tests added for new functionality. If not, please raise an issue to follow up.
• Documentation added/updated, if needed.