docs: add flutter.md (#149)

* docs: update dart.md

* docs: add flutter.md

README.md

@@ -41,6 +41,7 @@ Quick Reference
 [Docker](./docs/docker.md)<!--rehype:style=background: rgb(72 143 223/var(\-\-bg\-opacity));-->
 [Dockerfile](./docs/dockerfile.md)<!--rehype:style=background: rgb(0 72 153/var(\-\-bg\-opacity));&class=tag&data-lang=Docker-->
 [Django](./docs/djiango.md)<!--rehype:style=background: rgb(12 75 51/var(\-\-bg\-opacity));&class=contributing tag&data-lang=Python-->
+[Flutter](./docs/flutter.md)<!--rehype:style=background: rgb(150 220 254/var(\-\-bg\-opacity));&class=contributing tag&data-lang=Dart-->
 [Golang](./docs/golang.md)<!--rehype:style=background: rgb(39 160 193/var(\-\-bg\-opacity));-->
 [GraphQL](./docs/graphql.md)<!--rehype:style=background: rgb(214 66 146/var(\-\-bg\-opacity));-->
 [INI](./docs/ini.md)<!--rehype:style=background: rgb(57 59 60/var(\-\-bg\-opacity));-->

docs/flutter.md

@@ -0,0 +1,11 @@
+Flutter 备忘清单
+===
+
+包含Flutter常用的组件、布局、方法等。初学者的完整快速参考
+
+入门
+---
+
+### 介绍 (卡片)
+
+卡片内容

scripts/assets/flutter.svg

@@ -0,0 +1,12 @@
+<svg viewBox="0 0 256 317" xmlns="http://www.w3.org/2000/svg" preserveAspectRatio="xMidYMid" height="1em" width="1em">
+  <defs>
+    <linearGradient x1="3.952%" y1="26.993%" x2="75.897%" y2="52.919%" id="a">
+      <stop offset="0%"/>
+      <stop stop-opacity="0" offset="100%"/>
+    </linearGradient>
+  </defs>
+  <path fill="#47C5FB" d="M157.666 0 0 157.667l48.8 48.8L255.268.001zm-1.099 145.397L72.15 229.815l48.984 49.716 48.71-48.71 85.425-85.424z"/>
+  <path fill="#00569E" d="m121.133 279.531 37.082 37.082h97.052l-85.425-85.792z"/>
+  <path fill="#00B5F8" d="m71.6 230.364 48.801-48.801 49.441 49.258-48.71 48.71z"/>
+  <path fill-opacity=".8" fill="url(#a)" d="m121.133 279.531 40.56-13.459 4.029-31.13z"/>
+</svg>