compose-file: use JSON notation for entrypoint example

This format is also supported by YAML, and similar to
how it's used in the Dockerfile.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

compose/compose-file/compose-file-v1.md

@@ -186,13 +186,7 @@ The entrypoint can also be a list, in a manner similar to
 [dockerfile](/engine/reference/builder.md#entrypoint):
 
 ```yaml
-entrypoint:
+entrypoint: ["php", "-d", "memory_limit=-1", "vendor/bin/phpunit"]
-  - php
-  - -d
-  - zend_extension=/usr/local/lib/php/extensions/no-debug-non-zts-20100525/xdebug.so
-  - -d
-  - memory_limit=-1
-  - vendor/bin/phpunit
 ```
 
 > **Note**: Setting `entrypoint` both overrides any default entrypoint set

compose/compose-file/compose-file-v2.md

@@ -567,13 +567,7 @@ The entrypoint can also be a list, in a manner similar to
 [dockerfile](/engine/reference/builder.md#entrypoint):
 
 ```yaml
-entrypoint:
+entrypoint: ["php", "-d", "memory_limit=-1", "vendor/bin/phpunit"]
-  - php
-  - -d
-  - zend_extension=/usr/local/lib/php/extensions/no-debug-non-zts-20100525/xdebug.so
-  - -d
-  - memory_limit=-1
-  - vendor/bin/phpunit
 ```
 
 > **Note**

compose/compose-file/index.md

@@ -1011,13 +1011,7 @@ The entrypoint can also be a list, in a manner similar to
 [dockerfile](/engine/reference/builder.md#entrypoint):
 
 ```yaml
-entrypoint:
+entrypoint: ["php", "-d", "memory_limit=-1", "vendor/bin/phpunit"]
-  - php
-  - -d
-  - zend_extension=/usr/local/lib/php/extensions/no-debug-non-zts-20100525/xdebug.so
-  - -d
-  - memory_limit=-1
-  - vendor/bin/phpunit
 ```
 
 > **Note**