Added editor screenshot

Signed-off-by: Dimitris Kolovos <dkolovos@cs.york.ac.uk>
diff --git a/.DS_Store b/.DS_Store
deleted file mode 100644
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--- a/.DS_Store
+++ /dev/null
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diff --git a/mkdocs/docs/assets/images/emfatic-editor.png b/mkdocs/docs/assets/images/emfatic-editor.png
new file mode 100644
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diff --git a/mkdocs/docs/index.md b/mkdocs/docs/index.md
index 935aa75..7a87a7f 100644
--- a/mkdocs/docs/index.md
+++ b/mkdocs/docs/index.md
@@ -4,6 +4,8 @@
 (meta-)models. This page details the syntax of Emfatic and the mapping between
 Emfatic declarations and the corresponding Ecore constructs.
 
+![](assets/images/emfatic-editor.png)
+
 ## Packages
 
 Emfatic programs are shown in boxes as in the example