Update README to address missing entry script The README.md previously referenced a script 'generate-llmstxt-crawl4ai.py' for all command examples. This script is not present in the repository. This commit updates the README to: - Add a prominent note in 'Quick Start', 'Command Line Options', and 'Example Output' sections explaining the missing script. - Suggest potential reasons and guide the user on how to proceed, such as pointing to the 'llmsgen.generator' module for the core logic. - Preserve existing command examples as they are likely correct if the script were present or recreated by the user. - Correct minor formatting issues arising from the insertions. #2