[elasticsearch] heap size is no longer defaulted to 1g (elastic#1135)

see elastic#1089

elasticsearch/README.md

@@ -115,7 +115,7 @@ support multiple versions with minimal changes.
 | `enableServiceLinks`               | Set to false to disabling service links, which can cause slow pod startup times when there are many services in the current namespace.                                                                                                                    | `true`                                          |
 | `envFrom`                          | Templatable string to be passed to the [environment from variables][] which will be appended to the `envFrom:` definition for the container                                                                                                               | `[]`                                            |
 | `esConfig`                         | Allows you to add any config files in `/usr/share/elasticsearch/config/` such as `elasticsearch.yml` and `log4j2.properties`. See [values.yaml][] for an example of the formatting                                                                        | `{}`                                            |
-| `esJavaOpts`                       | [Java options][] for Elasticsearch. This is where you should configure the [jvm heap size][]                                                                                                                                                              | `-Xmx1g -Xms1g`                                 |
+| `esJavaOpts`                       | [Java options][] for Elasticsearch. This is where you could configure the [jvm heap size][]                                                                                                                                                              | `""`                                 |
 | `esMajorVersion`                   | Deprecated. Instead, use the version of the chart corresponding to your ES minor version. Used to set major version specific configuration. If you are using a custom image and not running the default Elasticsearch version you will need to set this to the version you are running (e.g. `esMajorVersion: 6`)                                   | `""`                                            |
 | `extraContainers`                  | Templatable string of additional `containers` to be passed to the `tpl` function                                                                                                                                                                          | `""`                                            |
 | `extraEnvs`                        | Extra [environment variables][] which will be appended to the `env:` definition for the container                                                                                                                                                         | `[]`                                            |