Overhaul bool documentation

[Mickeon]

Continuation of similar past efforts that aim for the same goal of refreshing the documentation up a notch.
Albeit the page is small, I did spend the whole day shaking off the rust.

• Made the wording match how other classes are documented more closely;
• Changed most self-referential mentions of "bool" to "boolean";
• In the codeblock examples:
  • Show to define can_shoot;
  • Make is_reloading a method. Its name matches Godot's method naming scheme more than properties.
  • Update C# examples to match the language's naming scheme.
• Briefly document short-circuit evaluation;
• Document how to deduce built-in methods and properties that return booleans.
• Add more detail to the bool(int) and bool(float) constructors.
• Mention that != for booleans is essentially the logical XOR;
  • This fact has been mentioned... many times already:
  • Missing Bool XOR from GDscript #18816
  • XOR #34455
  • XOR operator '^' for bools #22740
  • Add logical XOR to GDScript #76191
  • Add XOR operator to GDScript godot-proposals#3849...
  • Yet it was never even lightly documented for the less experienced users.

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Feedback is very, very welcome.

[Mickeon]

Pushed a commit to apply both aforementioned suggestions.

[MewPurPur]

Only this

[Mickeon]

Yeah.

[akien-mga]

Thanks!