Add api documentation

doc/API.md

@@ -0,0 +1,100 @@
+# Api
+
+## init
+
+Initialize eruda.
+
+### Options
+
+|Name             |Type        |Desc                                                                                     |
+|-----------------|------------|-----------------------------------------------------------------------------------------|
+|container        |element     |Container element. If not set, it will append an element directly under html root element|
+|tool             |string array|Choose which default tools you want, by default all will be added                        |
+|autoScale=true   |boolean     |Auto scale eruda for different viewport settings                                         |
+|useShadowDom=true|boolean     |Use shadow dom for css encapsulation                                                     |
+
+```javascript
+var el = document.createElement('div');
+document.body.appendChild(el);
+
+eruda.init({
+    container: el,
+    tool: ['console', 'elements'],
+    useShadowDom: true,
+    autoScale: true
+});
+```
+
+## destroy
+
+Destory eruda. 
+
+Note: You can call **init** method again after destruction.
+
+```javascript
+eruda.destroy();
+```
+
+## scale
+
+Set or get scale.
+
+```javascript
+eruda.scale(); // -> 1
+eruda.scale(1.5);
+```
+
+## position
+
+Set or get entry button position.
+
+It will not take effect if given pos is out of range.
+
+```javascript
+eruda.position({x: 20, y: 20});
+eruda.position(); // -> {x: 20, y: 20}
+```
+
+## get
+
+Get tool, eg. console, elements panels.
+
+```javascript
+var console = eruda.get('console');
+console.log('eruda');
+```
+
+## add
+
+Add tool.
+
+```javascript
+eruda.add(eruda.Tool.extend({
+    name: 'test'
+}));
+```
+
+## remove
+
+Remove tool.
+
+```javascript
+eruda.remove('console');
+```
+
+## show
+
+Show eruda panel.
+
+```javascript
+eruda.show();
+eruda.show('console');
+```
+
+## hide
+
+Hide eruda panel.
+
+```javascript
+eruda.hide();
+```