Remove imgur links, as they're now inaccessible in the United Kingdom (#73)

Author: jamielinux

static/img/widget-v1-completed-dark.png

@@ -190,4 +190,4 @@ We created an example app which you can view [here](https://github.com/FriendlyC
 
 #### Example App screenshot
 
-![Example App Screenshot](https://i.imgur.com/GJxlpZ6.png)
+![Example App Screenshot](/img/widget-v1-flutter.png)

static/img/widget-v1-flutter.png

@@ -4,7 +4,7 @@ The styling of Friendly Captcha is done in plain CSS, and you can change it howe
 
 ## Dark mode
 
-![Friendly Captcha widget finished screenshot](https://i.imgur.com/HlMY7QM.png) ![Friendly Captcha widget finished screenshot dark mode](https://i.imgur.com/UgqOJaB.png)
+![Friendly Captcha widget finished screenshot](/img/widget-v1-completed.png) ![Friendly Captcha widget finished screenshot dark mode](/img/widget-v1-completed-dark.png)
 
 Friendly Captcha ships with two built-in themes, by adding the `dark` class to your `frc-captcha` element you can enable dark mode:
 
@@ -26,4 +26,4 @@ If any HTML element with id `frc-style` is present on the HTML document, the ori
  <link rel="stylesheet" id="frc-style" href="/my-custom-widget-theme.css">
 ```
 
-Alternatively, if you are using the library approach, you can use the `skipStyleInjection` option to prevent a stylesheet from getting injected.
+Alternatively, if you are using the library approach, you can use the `skipStyleInjection` option to prevent a stylesheet from getting injected.

static/img/widget-v1-solving.png

@@ -9,8 +9,8 @@ Friendly Captcha is a service that protects websites from bots and abuse in a pr
 This site contains the technical documentation that will help you integrate the Friendly Captcha's anti-abuse service into your website. Integration entails adding a widget to the websites you want to protect. The Friendly Captcha widget looks like this:
 
 <figure style={{ textAlign: 'center' }}>
-    <img src="https://i.imgur.com/BNRdsxS.png" alt="Friendly Captcha widget solving screenshot" />
-    <img src="https://i.imgur.com/HlMY7QM.png" alt="Friendly Captcha widget finished screenshot" />
+    <img src="/img/widget-v1-solving.png" alt="Friendly Captcha widget solving screenshot" />
+    <img src="/img/widget-v1-completed.png" alt="Friendly Captcha widget finished screenshot" />
     <figcaption><i>Screenshots of the Friendly Captcha widget</i></figcaption>
 </figure>