Merge pull request #599 from thepriefy/priefy-issue-597

Add a .env_sample file, update gitignore, update README.md

.env_sample

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

.gitignore

@@ -323,4 +323,6 @@ $RECYCLE.BIN/
 *.lnk
 
 # Code
-/.vscode
+/.vscode
+
+.env

README.md

@@ -84,6 +84,18 @@ Click the "New" button beneath the User Variables list. Give it the name `NAME_O
 
 For value, insert your SendGrid API key. Click "Ok", and once again in the Variable Overview and lastly, close the system properties window.
 
+For other Windows version, you can set an environment variable like this:
+
+```csharp
+var setKey = Environment.SetEnvironmentVariable("NAME_OF_THE_ENVIRONMENT_VARIABLE_FOR_YOUR_SENDGRID_KEY", value);
+```
+
+For example,
+
+```csharp
+var setKey = Environment.SetEnvironmentVariable("SENDGRID_API_KEY", YOUR_API_KEY);
+```
+
 You may need to restart your IDE to make use of the new variable.
 
 Now, if all went well, you can access the just added variable in your C# SendGrid projects! Ready for some examples?
@@ -263,4 +275,4 @@ sendgrid-csharp is guided and supported by the SendGrid [Developer Experience Te
 sendgrid-csharp is maintained and funded by SendGrid, Inc. The names and logos for sendgrid-csharp are trademarks of SendGrid, Inc.
 
 # License
-[The MIT License (MIT)](LICENSE.txt)
+[The MIT License (MIT)](LICENSE.txt)