Fix doc links, added screenshots

Author: n7studios

.github/docs/coding-standards.png

@@ -4,8 +4,8 @@ Contributions of any kind are welcome! If you've found a bug or have a feature r
 
 To make changes yourself, follow these steps:
 
-1. Follow the [Setup Guide](SETUP.MD) to set up your environment and clone this repository
-2. Follow the [Development Guide](DEVELOPMENT.MD) to create a branch and make changes
-3. Refer to the [Testing Guide](TESTING.MD) to write applicable unit tests and submit your pull request.
+1. Follow the [Setup Guide](SETUP.md) to set up your environment and clone this repository
+2. Follow the [Development Guide](DEVELOPMENT.md) to create a branch and make changes
+3. Refer to the [Testing Guide](TESTING.md) to write applicable unit tests and submit your pull request.
 
 Thanks!

.github/docs/phpstan.png

@@ -51,13 +51,13 @@ or `ServerException` (for 5xx errors).
 
 ```php
 try {
-	$forms = $api->add_subscriber_to_form('invalid-form-id');
+    $forms = $api->add_subscriber_to_form('invalid-form-id');
 } catch (GuzzleHttp\Exception\ClientException $e) {
-	// Handle 4xx client errors.
+    // Handle 4xx client errors.
     die($e->getMessage());
 } catch (GuzzleHttp\Exception\ServerException $e) {
-	// Handle 5xx server errors.
-	die($e->getMessage());
+    // Handle 5xx server errors.
+    die($e->getMessage());
 }
 ```
 
@@ -66,16 +66,16 @@ For a more detailed error message, it's possible to fetch the API's response whe
 ```php
 // Errors will be thrown as Guzzle's ClientException or ServerException.
 try {
-	$forms = $api->form_subscribe('invalid-form-id');
+    $forms = $api->form_subscribe('invalid-form-id');
 } catch (GuzzleHttp\Exception\ClientException $e) {
-	// Handle 4xx client errors.
-	// For ClientException, it's possible to inspect the API's JSON response
-	// to output an error or handle it accordingly.
+    // Handle 4xx client errors.
+    // For ClientException, it's possible to inspect the API's JSON response
+    // to output an error or handle it accordingly.
     $error = json_decode($e->getResponse()->getBody()->getContents());
     die($error->message); // e.g. "Entity not found".
 } catch (GuzzleHttp\Exception\ServerException $e) {
-	// Handle 5xx server errors.
-	die($e->getMessage());
+    // Handle 5xx server errors.
+    die($e->getMessage());
 }
 ```
 

CONTRIBUTING.md

@@ -38,7 +38,7 @@ If you're new to this, use [GitHub Desktop](https://desktop.github.com/) or [Tow
 
 ### Configure Testing Environment
 
-Copy the `.env.example` file to `.env` in the root of this repository, changing folder and database credentials as necessary:
+Copy the `.env.example` file to `.env` in the root of this repository, adding your ConvertKit API keys.
 
 ```
 CONVERTKIT_API_KEY_NO_DATA=
@@ -107,8 +107,6 @@ correctly setup your environment:
 vendor/bin/phpunit
 ```
 
-![PHPUnit Test Results](/.github/docs/phpunit.png?raw=true)
-
 Don't worry if you don't understand these commands; if your output looks similar to the above screenshot, and no test is prefixed with `E`, 
 your environment is setup successfully.
 
@@ -117,8 +115,8 @@ your environment is setup successfully.
 In the root directory, run the following commands to run PHP_CodeSniffer, which will check the code meets PHP Coding Standards:
 
 ```bash
-vendor/bin/phpcs
-vendor/bin/phpcs --standard=phpcs.tests.xml
+vendor/bin/phpcs -s -v
+vendor/bin/phpcs -s -v --standard=phpcs.tests.xml
 ```
 
 ![Coding Standards Test Results](/.github/docs/coding-standards.png?raw=true)