sanitize the code

docs/selector.md

@@ -1,7 +1,7 @@
 # Selector
 
 Deployer uses the selector to choose hosts. Each host can have a set of labels. 
-Labels are key-value pairs.
+Labels are key-value pairs. 
 
 For example, `stage: production` or `role: web`. 
 
@@ -25,7 +25,6 @@ host('db.example.com')
 ```
 or use `->addLables()` method to add labels to the existing host.
 
-
 Now let's define a task to check labels:
 
 ```php
@@ -78,7 +77,6 @@ task info
 
 As you can see, both hosts are selected (as both of them have the `env: prod` label).
 
-
 We can use `&` to define **AND**. For example, `type=web & env=prod` is a selector
 for hosts with `type: web` **AND** `env: prod` labels.
 
@@ -168,8 +166,6 @@ task('info', function () {
 })->select('type=web|db,env=prod');
 ```
 
-
-
 ## Labels in YAML
 
 You can also define labels in a YAML recipe. For example: