Incorporate comparison with other proposals into the README

Also, remove obsolte comparison between thsi proposal and
others, both in the sense of (i) deleting the file,
COMPARISON,md, that talks about that, and (ii) remove talk
of doing another version of BigInt plus a few other
proposals.

README.md

@@ -354,6 +354,10 @@ Mike Cowlishaw’s excellent [Decimal FAQ](http://speleotrove.com/decimal/decifa
 
 One notable exception is supporting trailing zeroes: Although Mike presents some interesting use cases, the Decimal champion group does not see these as being worth the complexity both for JS developers and implementors. Instead, Decimal values could be lossly represented as rationals, and are “canonicalized”.
 
+## Relationship of Decimal to other TC39 proposals
+
+This proposal can be seen as a follow-on to [BigInt](https://github.com/tc39/proposal-bigint/), which brought arbitrary-sized integers to JavaScript, and will be fully standardized in ES2020. However, unlike BigInt, Decimal (i) does not propose to intrduce a new primitive data type, (ii) does not propose operator overloading (which BigInt does support), and (iii) does not offer new syntax (numeric literla), which BigInt does add (e.g., `2345n`).
+
 ## Implementations
 
 + Experimental implementation in [QuickJS](https://bellard.org/quickjs/), from release 2020-01-05 (use the `--bignum` flag)