add: migrate to 9.0

Migrate-to-9.md

@@ -0,0 +1,19 @@
+LiquidJS 9.0.0 has some fundamental improvements, including bugfixes, new features and performance improvement due to higher target(see #137). There're also some breaking changes.
+
+Features:
+
+* Sync rendering: renderSync, parseAndRenderSync, renderFileSync
+* New utils: Expression
+
+Fixes:
+
+* Rewrite boolean expression evaluation order, #130
+* `break` and `continue` tags omitting output before them, #123
+* Fixes errors in reactjs demo during yarn install, #145
+* promise typed Drops are not await-ed some times
+
+REAKING CHANGE:
+
+* Liquid is no longer a default export, use `import {Liquid} from 'liquidjs'` instead, `Liquid` in the UMD bundle is also changed to `window.liquidjs.Liquid`
+* The duplicate `Liquid.evalValue` is removed, use `liquid.evalValue` instead
+* Shipped to Node.js 8, the dist/liquid.cjs.js (main) nolonger supports Node.js 6, other bundles are also provided via dist/liquid.esm.js, dist/liquid.js (ES5 umd) and liquid.min.js (minified ES5 umd)

Register-Filters-Tags.md

@@ -23,7 +23,7 @@ engine.registerTag('upper', {
         this.str = tagToken.args; // name
     },
     render: async function(scope, hash) {
-        var str = await Liquid.evalValue(this.str, scope); // 'alice'
+        var str = await this.liquid.evalValue(this.str, scope); // 'alice'
         return str.toUpperCase()  // 'Alice'
     }
 });

_Sidebar.md

@@ -7,6 +7,7 @@
     * [Whitespace Control](/harttle/liquidjs/wiki/Whitespace-Control)
     * [Register Filters/Tags](/harttle/liquidjs/wiki/Register-Filters-Tags)
     * [Write a Plugin](/harttle/liquidjs/wiki/Write-a-Plugin)
+    * [Migrate to 9.0.0](/harttle/liquidjs/wiki/Migrate-to-9)
 * API
     * [Options](https://harttle.github.io/liquidjs/interfaces/_liquid_options_.liquidoptions.html)
     * [Builtin Filters](/harttle/liquidjs/wiki/Builtin-Filters)