doc: add discovered intra-doc links and urls with usages within repo to rustdoc of `near-sdk`

[dj8yfo]

in scope of review of #1259 a number of suggestions to add links to rustdoc
was commented on pr,
and separated from #1259 as current issue in order to not block the pr needlessly

---

The majority of intra-doc linking suggestions have been handled by @PolyProgrammist in #1262 .
The remaining comments with #[callback_...] attributes now depend on #1300

[dj8yfo]

The majority of intra-doc linking suggestions have been handled by @PolyProgrammist in #1262 .

Putting the remaining few here in the form of screenshots:

• 3 https://github.com/near/near-sdk-rs/pull/1259/files/90b43a71a329631b44d9cb88e126e8397623e877#r1861047690
  (scope of this was moved to doc: #[near(contract_state)] doc should link to [store] and [collections] modules #1304
• 1 https://github.com/near/near-sdk-rs/pull/1259/files/90b43a71a329631b44d9cb88e126e8397623e877#r1859335172
  
• 2 https://github.com/near/near-sdk-rs/pull/1259/files/90b43a71a329631b44d9cb88e126e8397623e877#r1860723942
  
• 4 https://github.com/near/near-sdk-rs/pull/1259/files/90b43a71a329631b44d9cb88e126e8397623e877#r1861306186