Polish "Add consistent quotes in YAML samples of reference doc"

See gh-28911

spring-boot-project/spring-boot-docs/src/docs/asciidoc/deployment/cloud.adoc

@@ -124,12 +124,12 @@ You can configure a sleep execution in a preStop handler to avoid requests being
 This sleep should be long enough for new requests to stop being routed to the pod and its duration will vary from deployment to deployment.
 The preStop handler can be configured by using the PodSpec in the pod's configuration file as follows:
 
-[source,yml,indent=0,subs="verbatim"]
+[source,yaml,indent=0,subs="verbatim"]
 ----
 	spec:
 	  containers:
-	  - name: example-container
-	    image: example-image
+	  - name: "example-container"
+	    image: "example-image"
 	    lifecycle:
 	      preStop:
 	        exec:
@@ -379,26 +379,26 @@ Normally, you put this file in `src/main/appengine`, and it should resemble the
 
 [source,yaml,indent=0,subs="verbatim"]
 ----
-	service: default
+	service: "default"
 
-	runtime: java
-	env: flex
+	runtime: "java"
+	env: "flex"
 
 	runtime_config:
-	  jdk: openjdk8
+	  jdk: "openjdk8"
 
 	handlers:
-	- url: /.*
-	  script: this field is required, but ignored
+	- url: "/.*"
+	  script: "this field is required, but ignored"
 
 	manual_scaling:
 	  instances: 1
 
 	health_check:
-	  enable_health_check: False
+	  enable_health_check: false
 
 	env_variables:
-	  ENCRYPT_KEY: your_encryption_key_here
+	  ENCRYPT_KEY: "your_encryption_key_here"
 ----
 
 You can deploy the app (for example, with a Maven plugin) by adding the project ID to the build configuration, as shown in the following example: