Remove backbone callback documentation

[dplewis]

Old backbone callbacks (options.success, options.error) are only used in linkWith authentication and object.set validation now.

i.e

object.set("currentPlayer", player2, {
  error: function(objectAgain, error) {
    // The set failed validation.
  }
});

[ghost]

Danger run resulted in 1 fail and 1 markdown; to find out more, see the checks page.

Generated by 🚫 dangerJS

[codecov]

Codecov Report

Merging #1239 into master will increase coverage by 0.07%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master    #1239      +/-   ##
==========================================
+ Coverage   92.38%   92.46%   +0.07%     
==========================================
  Files          54       54              
  Lines        5318     5308      -10     
  Branches     1202     1198       -4     
==========================================
- Hits         4913     4908       -5     
+ Misses        405      400       -5     

Impacted Files	Coverage Δ
src/ParseGeoPoint.js	95.45% <ø> (ø)
src/ParseObject.js	90.94% <ø> (+0.44%)	⬆️
src/ParseQuery.js	96.06% <ø> (ø)
src/ParseUser.js	83.16% <ø> (ø)

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[mtrezza]

lgtm 🚀