Add @openzeppelin/contracts as alternative package name (#1840)

* Rename package and repository name from docs and scripts

* undo root package rename

* add @openzeppelin/contracts as subpackage with release automation

* synchronize @openzeppelin/contracts version

* remove private field from package.json

* make file patterns absolute

* change wording of a comment

* use a saner version script

.github/ISSUE_TEMPLATE/feature_request.md

@@ -1,6 +1,6 @@
 ---
 name: Feature request
-about: Suggest an idea for OpenZeppelin
+about: Suggest an idea for OpenZeppelin Contracts
 
 ---
 
@@ -11,4 +11,4 @@ about: Suggest an idea for OpenZeppelin
 <!-- Please describe your feature request in detail. -->
 
 <!-- Make sure that you have reviewed the OpenZeppelin Contributor Guidelines. -->
-<!-- https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md -->
+<!-- https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/CONTRIBUTING.md -->

.github/PULL_REQUEST_TEMPLATE.md

@@ -13,7 +13,7 @@ Fixes #
 
 <!-- 3. Before submitting, please make sure that you have:
   - reviewed the OpenZeppelin Contributor Guidelines
-    (https://github.com/OpenZeppelin/openzeppelin-solidity/blob/master/CONTRIBUTING.md),
+    (https://github.com/OpenZeppelin/openzeppelin-contracts/blob/master/CONTRIBUTING.md),
   - added tests where applicable to test new functionality,
   - made sure that your contracts are well-documented,
   - run the Solidity linter (`npm run lint:sol`) and fixed any issues,