[skywalking-docker] 31/45: Update README.md

[wu...@apache.org]

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wusheng pushed a commit to branch master
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commit f54f91d105ccfeaf408ef3aefa8594eb3f9aab06
Author: 吴晟 Wu Sheng <wu...@foxmail.com>
AuthorDate: Thu Oct 17 22:37:12 2019 +0300

    Update README.md
---
 6/6.4/oap/README.md | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/6/6.4/oap/README.md b/6/6.4/oap/README.md
index 41a0c2c..dd665bc 100644
--- a/6/6.4/oap/README.md
+++ b/6/6.4/oap/README.md
@@ -23,6 +23,9 @@ $ docker run --name oap --restart always -d -e SW_STORAGE=elasticsearch -e SW_ST
 
 We could set up environment variables to configure this image. Most of them are defined in [backend-setup](https://github.com/apache/skywalking/blob/v6.4.0/docs/en/setup/backend/backend-setup.md), but Apache SkyWalking Docker Image adds extra environment variables to help the user to compose it properly. The details are located in [docker-entrypoint.sh](docker-entrypoint.sh)
 
+## SW_ENVOY_ALS_ENABLED
+No default value, set it to `true` to open ALS solution of SkyWalking.
+
 ## SW_CLUSTER
 Default value is `standalone`, avaliable values are: