Review fixes: MyST markup, language, and grammar

[rkratky]

Summary

Review fixes for PR canonical#135 (Add a basic Spring AI tutorial).

Changes

MyST markup:

• Added two blank lines above each heading (except the first)
• Added one blank line above/below all code blocks, lists, admonitions, and images
• Converted all terminal CLI commands to the {terminal} directive (sphinx-terminal)
• Converted all code blocks to {code-block} directive with :caption: for file-named blocks
• Converted log/error output blocks to {terminal} with :output-only:
• Used {code-block} none for web UI Q&A examples

Language and grammar:

• Reworded future tense to present simple ("We will use" -> "We use")
• Reworded "you may" / "if" / conditionals to imperative form
• Removed "please" from prose
• Fixed "Initialzing" -> "Initializing"
• Fixed "inference with it" -> "perform inference with it"
• Removed "should" where it expressed uncertainty ("should be logged" -> "are logged")

Semantic markup:

• Package names: {pkg}
• File/directory names: {file}
• Commands: {command}

Serial comma:

• Added serial comma to lists of 3+ items
• Did not apply to 2-item lists

Other:

• Ordered lists use 1. for all items
• No {gui} role available; used plain backticks for the beta channel name