Convert plugin examples to codesandbox (#1316)

* Migrate plugin examples to codesandbox

* Fix examples

* Add links to plugin examples

Author: m4theushw

docs/jss-plugin-camel-case.md

@@ -19,3 +19,7 @@ Compiles to:
   font-size: 12px;
 }
 ```
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-camel-case?fontsize=14)

docs/jss-plugin-compose.md

@@ -179,3 +179,7 @@ It renders to:
 - It doesn't work within [global Style Sheets](https://github.com/cssinjs/jss/tree/master/packages/jss-plugin-global).
 - It does not work inside of [nested rules](https://github.com/cssinjs/jss/tree/master/packages/jss-plugin-nested).
 - When composing local rules, they need to be defined first. Otherwise, you get wrong CSS selector order and specificity.
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-compose?fontsize=14)

docs/jss-plugin-default-unit.md

@@ -60,3 +60,7 @@ Compiles to:
   z-index: 1;
 }
 ```
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-default-unit?fontsize=14)

docs/jss-plugin-expand.md

@@ -400,3 +400,7 @@ const styles = {
   }
 }
 ```
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-expand?fontsize=14)

docs/jss-plugin-extend.md

@@ -76,5 +76,4 @@ const styles = {
 
 ### Demo
 
-[Simple demo](http://cssinjs.github.io/examples/plugins/jss-extend/simple/)
-[Multi objects demo](http://cssinjs.github.io/examples/plugins/jss-extend/multi/)
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-extend?fontsize=14)

docs/jss-plugin-global.md

@@ -73,3 +73,7 @@ Compiles to:
   color: red;
 }
 ```
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-global?fontsize=14)

docs/jss-plugin-isolate.md

@@ -183,7 +183,7 @@ jss.use(
 
 ### Demo
 
-[Simple](http://cssinjs.github.io/examples/plugins/jss-plugin-isolate/simple/index.html)
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-isolate?fontsize=14)
 
 ### Reseted properties
 

docs/jss-plugin-nested.md

@@ -142,3 +142,7 @@ Compiles to:
   background: red;
 }
 ```
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-nested?fontsize=14)

docs/jss-plugin-props-sort.md

@@ -19,3 +19,7 @@ Compiles to:
   border-left: 1px solid red;
 }
 ```
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-props-sort?fontsize=14)

docs/jss-plugin-rule-value-function.md

@@ -66,3 +66,7 @@ const sheet = jss
 
 sheet.update({color: 'red'})
 ```
+
+### Demo
+
+[CodeSandbox](//codesandbox.io/s/github/cssinjs/jss/tree/master/examples/plugins/jss-plugin-rule-value-function?fontsize=14)