Drop dollar sign on install command (#68)

Author: sandervanhooft

README.md

@@ -51,7 +51,7 @@ if ($validator->isValid($message)) {
 
 The SNS Message Validator can be installed via [Composer][].
 
-    $ composer require aws/aws-php-sns-message-validator
+    composer require aws/aws-php-sns-message-validator
 
 ## Getting Help
 
@@ -176,4 +176,4 @@ implementation][] in Version 2 of the [AWS SDK for PHP][].
 
 ## Contributing
 
-We work hard to provide a high-quality and useful SDK for our AWS services, and we greatly value feedback and contributions from our community. Please review our [contributing guidelines](./CONTRIBUTING.md) before submitting any issues or pull requests to ensure we have all the necessary information to effectively respond to your bug report or contribution.
+We work hard to provide a high-quality and useful SDK for our AWS services, and we greatly value feedback and contributions from our community. Please review our [contributing guidelines](./CONTRIBUTING.md) before submitting any issues or pull requests to ensure we have all the necessary information to effectively respond to your bug report or contribution.