Review fixes: MyST markup, language, and grammar

[rkratky]

Summary

Review fixes for PR canonical#139 (Add a tutorial for tool-calling with Spring AI).

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 output blocks to {terminal} with :output-only:
• Used {code-block} none for web UI Q&A examples
• Indented all list item content (including code blocks, admonitions, and inter-item text) to align with 1. prefix

Language and grammar:

• Reworded future tense to present simple ("We will augment" -> "We augment", "This tutorial will reuse" -> "This tutorial reuses", "we will use" -> "we use")
• Reworded "you may" / "may be" / "if" / conditionals to imperative form
• Fixed "dif ficult" -> "difficult"
• Fixed "lets" -> "let's"
• Removed "should" where expressing uncertainty ("should be seen" -> "is displayed", "should be expected" -> "is expected")

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
• "This is not a full source listing of DemoChatService.java" kept (file name part of sentence, not a filename-only line)