Added example file, updated .gitignore and README.

Author: dhsrocha

.gitignore

@@ -1,6 +1,11 @@
-.env
-*.lock
+# Composer
 vendor/
+*.phar
+*.lock
+
+# Jetbrains Idea
 *.old
 .idea/
-*.phar
+
+# Environment files
+.env/*.*

README.md

@@ -138,6 +138,8 @@ print $response->body();
 
 - [Example Code](https://github.com/sendgrid/php-http-client/tree/master/examples)
 
+You can use the ```.env_example``` file located at "examples" folder. Just copy it to a ```.env``` folder ou can put on your project's root.
+
 <a name="roadmap"></a>
 # Roadmap
 

examples/.env_sample

@@ -0,0 +1 @@
+export SENDGRID_API_KEY=''