Merge pull request #1650 from nventuro/missing-changelog-data

Added PR links for 2.2.0 changelog entries.

CHANGELOG.md

@@ -3,20 +3,20 @@
 ## 2.2.0 (unreleased)
 
 ### New features:
- * `ERC20`: added internal `_approve(address owner, address spender, uint256 value)`, allowing derived contracts to set the allowance of arbitrary accounts.
- * `ERC20Metadata`: added internal `_setTokenURI(string memory tokenURI)`.
- * `ERC20Snapshot`: create snapshots on demand of the token balances and total supply, to later retrieve and e.g. calculate dividends at a past time.
+ * `ERC20`: added internal `_approve(address owner, address spender, uint256 value)`, allowing derived contracts to set the allowance of arbitrary accounts. ([#1609](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1609))
+ * `ERC20Metadata`: added internal `_setTokenURI(string memory tokenURI)`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
+ * `ERC20Snapshot`: create snapshots on demand of the token balances and total supply, to later retrieve and e.g. calculate dividends at a past time. ([#1617](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1617))
 
 ### Improvements:
- * Upgraded the minimum compiler version to v0.5.2: this removes many Solidity warnings that were false positives.
- * `Counter`'s API has been improved, and is now used by `ERC721` (though it is still in `drafts`).
- * `ERC721`'s transfers are now more gas efficient due to removal of unnecessary `SafeMath` calls.
- * Fixed variable shadowing issues.
+ * Upgraded the minimum compiler version to v0.5.2: this removes many Solidity warnings that were false positives. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
+ * `Counter`'s API has been improved, and is now used by `ERC721` (though it is still in `drafts`). ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+ * `ERC721`'s transfers are now more gas efficient due to removal of unnecessary `SafeMath` calls. ([#1610](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1610))
+ * Fixed variable shadowing issues. ([#1606](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1606))
 
 ### Bugfixes:
 
 ### Breaking changes:
- * `TokenMetadata` (in drafts) has been renamed to `ERC20Metadata`.
+ * `TokenMetadata` (in drafts) has been renamed to `ERC20Metadata`. ([#1618](https://github.com/OpenZeppelin/openzeppelin-solidity/pull/1618))
 
 ## 2.1.2 (2019-17-01)
  * Removed most of the test suite from the npm package, except `PublicRole.behavior.js`, which may be useful to users testing their own `Roles`.