Removed references to npm-*.*.* and releases branches from docs (#626)

I'll also update the Releases wiki page to no longer suggest them.

Fixes #610

README.md

@@ -13,11 +13,6 @@ A set of [TSLint](https://github.com/palantir/tslint) rules used on some Microso
 npm install tslint-microsoft-contrib --save-dev
 ```
 
-Alternately, you can download the files directly from GitHub: see [npm-5.2.1](https://github.com/Microsoft/tslint-microsoft-contrib/tree/npm-5.2.1).
-
-...or use the [`releases`](https://github.com/Microsoft/tslint-microsoft-contrib/tree/releases) branch, which is available online.
-You can use that build by setting your npm version of `tslint-microsoft-contrib` to `git://github.com/Microsoft/tslint-microsoft-contrib.git#releases`.
-
 ## TSLint and corresponding tslint-microsoft-contrib version
 
 | TSLint version | tslint-microsoft-contrib version              |

build-tasks/validate-documentation.js

@@ -24,16 +24,6 @@ getAllFormatterNames().forEach(formatterName => {
     }
 });
 
-if (readmeText.indexOf('[npm-' + packageJson.version + ']') === -1) {
-    validationErrors.push(
-        'Version not documented in README.md correctly.\n' +
-            'package.json declares: ' +
-            packageJson.version +
-            '\n' +
-            'README.md declares something different.'
-    );
-}
-
 if (validationErrors.length > 0) {
     console.log(yellowBright(validationErrors.join('\n')));
     process.exit(1);