Improve documentation of operators

[moble]

I've always found the documentation of operators a little disjointed and incomplete; this PR aims to improve the situation.

• Add missing items to the precedence table
  • Adjoint operator goes after :: and before exponentiation
  • Juxtaposition of numeric literals goes after unary operators and before bitshifts
  • Arrows go between || and ?
  • New footnote explains exceptions to exponentiation precedence
  • New footnote explains non-associativity of comparisons, but notes chaining
• Add more complete lists of operators
  • Include all operators defined in Base
  • Include operators that are available but not defined in Base, set off by parentheses
• Operator suffixes
  • Note that new operators can be defined with suffixes
  • Explain what those prefixes are
  • Show an example
• Provide some links between disjoint pages
  • Link from Manual > Variables to operator section
  • Link from Manual > Integers and Floating-Point Numbers to operator section
  • Link from Manual > Functions to operator section
  • Link back to functions page when noting that operators are functions.

[moble]

Given that the documentation previously said that a space was required in expressions like the +ᵃx discussed above, I guess we would argue that just parsing it as +ᵃ x is actually a bug, which can be fixed by modifying the parser. As such, I don't want to weaken that language, so I've reverted my change to keep the stronger language.

[Bhupendra-glitch]

hello @moble @stevengj
thanks for working on this — this is a really helpful cleanup of the operator docs.

I’ve been reading through the changes and I’m interested in contributing here as well. In particular, I’d like to help by adding a few concrete examples to clarify operator suffixes and chaining behavior, and double-checking that the precedence/associativity descriptions match actual Julia behavior.

Let me know if you’d prefer examples in a specific section or if there are other gaps you’d like help filling. Happy to open a small follow-up commit if that’s useful.

[moble]

@Bhupendra-glitch Thanks! I'm hoping that this PR could be merged soon, so I think it makes more sense to open that as a separate PR. Feel free to ping me on it!

@stevengj Does this look ready to go to you?

[fingolfin]

This looks a nice improvement, thanks a lot!

I've left a bunch of comments. Several are clearly "out of scope" in that they affect text that was there before your PR. These are not meant to block this PR, I just thought you might be able to address them, given that you already familiarized yourself with this. Of course that does not at all mean you have to, or have to do it in this PR.

The one change I care about is explaining the meaning of the parenthesis in the table before the table. Everything else is optional.

[moble]

@fingolfin Thanks for your review. You raise good points. I've added a commit that addresses at least some of them, but I still have to go through each of your points to make sure I haven't missed any. I'll respond to them above (though I'm really busy for the rest of the day, so I might not get to everything today).

[fingolfin]

Awesome!