Fixed linux tar asc and sha512 download address
diff --git a/docs/downloads/README.md b/docs/downloads/README.md
index e829429..7abbe45 100755
--- a/docs/downloads/README.md
+++ b/docs/downloads/README.md
@@ -10,15 +10,15 @@
|:---:|:--:|:--:|:--:|
| Jan 29th, 2019 | 6.0.0-GA | Source codes| [[src]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA-src.tgz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA-src.tgz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA-src.tgz.sha512)|
| | | Windows| [[zip]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.zip) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.tar.gz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.tar.gz.sha512)|
-| | | Linux | [[tar]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.tar.gz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.zip.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.zip.sha512)|
+| | | Linux | [[tar]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.tar.gz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.tar.gz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-GA/apache-skywalking-apm-incubating-6.0.0-GA.tar.gz.sha512)|
| | | Document| [Document](https://github.com/apache/incubator-skywalking/blob/v6.0.0-GA/docs/README.md) |
| Dec 25th, 2018 | 6.0.0-beta | Source codes| [[src]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta-src.tgz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta-src.tgz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta-src.tgz.sha512)|
| | | Windows| [[zip]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.zip) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.tar.gz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.tar.gz.sha512)|
-| | | Linux | [[tar]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.tar.gz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.zip.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.zip.sha512)|
+| | | Linux | [[tar]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.tar.gz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.tar.gz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-beta/apache-skywalking-apm-incubating-6.0.0-beta.tar.gz.sha512)|
| | | Document| [Document](https://github.com/apache/incubator-skywalking/blob/v6.0.0-beta/docs/README.md) |
| Nov. 14th, 2018 | 6.0.0-alpha | Source codes| [[src]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha-src.tgz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha-src.tgz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha-src.tgz.sha512)|
| | | Windows| [[zip]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.zip) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.tar.gz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.tar.gz.sha512)|
-| | | Linux | [[tar]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.tar.gz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.zip.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.zip.sha512)|
+| | | Linux | [[tar]](http://www.apache.org/dyn/closer.cgi/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.tar.gz) [[asc]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.tar.gz.asc) [[sha512]](https://www.apache.org/dist/incubator/skywalking/6.0.0-alpha/apache-skywalking-apm-incubating-6.0.0-alpha.tar.gz.sha512)|
| | | Document| [Document](https://github.com/apache/incubator-skywalking/blob/v6.0.0-alpha/docs/README.md) |
