docs: github.md examples use `num_code_suggestions`, but the real config key is `num_code_suggestions_per_chunk` - documented overrides are silently ignored

Summary

docs/docs/installation/github.md (live at https://docs.pr-agent.ai/installation/github/) instructs users to set PR_CODE_SUGGESTIONS.NUM_CODE_SUGGESTIONS, pr_code_suggestions.num_code_suggestions, or num_code_suggestions = 6 in three different examples. The tool only reads num_code_suggestions_per_chunk, so every documented override is silently ignored.

Evidence

Docs (three locations):

• github.md:52 - PR_CODE_SUGGESTIONS.NUM_CODE_SUGGESTIONS: 6 # Increase number of code suggestions (GitHub Action env)
• github.md:383 - pr_code_suggestions.num_code_suggestions: "8" (a workflow example)
• github.md:462 - num_code_suggestions = 6 (a .pr_agent.toml example)

Code:

• pr_agent/settings/configuration.toml:218 defines num_code_suggestions_per_chunk=3
• pr_agent/tools/pr_code_suggestions.py:149 reads get_settings().pr_code_suggestions.num_code_suggestions_per_chunk

There is no num_code_suggestions config key (the only other hit is a comment string in pr_agent/algo/utils.py:919). Note that improve.md documents the key correctly as num_code_suggestions_per_chunk (improve.md:62, :312, :394), and configuration_reference.md:255 lists the right key too.

Impact

Users tuning the number of code suggestions via the GitHub integration docs see no effect and no warning.

Expected

Update the three examples in github.md to use num_code_suggestions_per_chunk (e.g. PR_CODE_SUGGESTIONS.NUM_CODE_SUGGESTIONS_PER_CHUNK).