Update quickstart img for dark mode (#118)

* fix graph diagram for dark mode

* add arrows json export for data-model.png

Author: johnymontana

images/dgraph/quickstart/arrows/data-model.json

@@ -0,0 +1,200 @@
+{
+  "style": {
+    "font-family": "sans-serif",
+    "background-color": "#ffffff",
+    "background-image": "",
+    "background-size": "100%",
+    "node-color": "#ffffff",
+    "border-width": 4,
+    "border-color": "#000000",
+    "radius": 50,
+    "node-padding": 5,
+    "node-margin": 2,
+    "outside-position": "auto",
+    "node-icon-image": "",
+    "node-background-image": "",
+    "icon-position": "inside",
+    "icon-size": 64,
+    "caption-position": "inside",
+    "caption-max-width": 200,
+    "caption-color": "#000000",
+    "caption-font-size": 50,
+    "caption-font-weight": "normal",
+    "label-position": "inside",
+    "label-display": "pill",
+    "label-color": "#000000",
+    "label-background-color": "#ffffff",
+    "label-border-color": "#000000",
+    "label-border-width": 4,
+    "label-font-size": 40,
+    "label-padding": 5,
+    "label-margin": 4,
+    "directionality": "directed",
+    "detail-position": "inline",
+    "detail-orientation": "parallel",
+    "arrow-width": 5,
+    "arrow-color": "#000000",
+    "margin-start": 5,
+    "margin-end": 5,
+    "margin-peer": 20,
+    "attachment-start": "normal",
+    "attachment-end": "normal",
+    "relationship-icon-image": "",
+    "type-color": "#000000",
+    "type-background-color": "#ffffff",
+    "type-border-color": "#000000",
+    "type-border-width": 0,
+    "type-font-size": 16,
+    "type-padding": 5,
+    "property-position": "outside",
+    "property-alignment": "colon",
+    "property-color": "#000000",
+    "property-font-size": 16,
+    "property-font-weight": "normal"
+  },
+  "nodes": [
+    {
+      "id": "n0",
+      "position": {
+        "x": 0,
+        "y": 0
+      },
+      "caption": "",
+      "style": {},
+      "labels": ["Movie"],
+      "properties": {
+        "Movie.title": "\"Star Wars: Episode IV - A New Hope\"",
+        "Movie.release_date": "1977-05-25"
+      }
+    },
+    {
+      "id": "n1",
+      "position": {
+        "x": -246.33151765748622,
+        "y": -186.9694039374689
+      },
+      "caption": "",
+      "style": {},
+      "labels": ["Person"],
+      "properties": {
+        "name": "\"George Lucas\""
+      }
+    },
+    {
+      "id": "n2",
+      "position": {
+        "x": 154.62597986768978,
+        "y": -267.8200533009611
+      },
+      "caption": "",
+      "style": {},
+      "labels": ["Genre"],
+      "properties": {
+        "Genre.name": "\"Sci-Fi\""
+      }
+    },
+    {
+      "id": "n3",
+      "position": {
+        "x": 480.95404779578973,
+        "y": -128.1614015906278
+      },
+      "caption": "",
+      "style": {},
+      "labels": ["Movie"],
+      "properties": {
+        "Movie.title": "\"Star Trek: The Motion Picture\"",
+        "Movie.release_date": "1979-12-07"
+      }
+    },
+    {
+      "id": "n4",
+      "position": {
+        "x": -289.3028951157313,
+        "y": 309.2519597353796
+      },
+      "caption": "",
+      "style": {},
+      "labels": ["Character"],
+      "properties": {
+        "Character.name": "\"Luke Skywalker\""
+      }
+    },
+    {
+      "id": "n5",
+      "position": {
+        "x": 0,
+        "y": 309.2519597353796
+      },
+      "caption": "",
+      "style": {},
+      "labels": ["Character"],
+      "properties": {
+        "Character.name": "\"Princess Leia\""
+      }
+    },
+    {
+      "id": "n6",
+      "position": {
+        "x": 289.3028951157313,
+        "y": 309.2519597353796
+      },
+      "caption": "",
+      "style": {},
+      "labels": ["Character"],
+      "properties": {
+        "Character.name": "\"Han Solo\""
+      }
+    }
+  ],
+  "relationships": [
+    {
+      "id": "n0",
+      "type": "Movie.director",
+      "style": {},
+      "properties": {},
+      "fromId": "n0",
+      "toId": "n1"
+    },
+    {
+      "id": "n1",
+      "type": "Movie.genre",
+      "style": {},
+      "properties": {},
+      "fromId": "n0",
+      "toId": "n2"
+    },
+    {
+      "id": "n2",
+      "type": "Movie.genre",
+      "style": {},
+      "properties": {},
+      "fromId": "n3",
+      "toId": "n2"
+    },
+    {
+      "id": "n3",
+      "type": "Movie.character",
+      "style": {},
+      "properties": {},
+      "fromId": "n0",
+      "toId": "n4"
+    },
+    {
+      "id": "n4",
+      "type": "Movie.character",
+      "style": {},
+      "properties": {},
+      "fromId": "n0",
+      "toId": "n5"
+    },
+    {
+      "id": "n5",
+      "type": "Movie.character",
+      "style": {},
+      "properties": {},
+      "fromId": "n0",
+      "toId": "n6"
+    }
+  ]
+}