fix some spelling mistakes (#2615)

apm-commons/apm-datacarrier/src/main/java/org/apache/skywalking/apm/commons/datacarrier/buffer/Channels.java

@@ -22,7 +22,7 @@ import org.apache.skywalking.apm.commons.datacarrier.callback.QueueBlockingCallb
 import org.apache.skywalking.apm.commons.datacarrier.partition.IDataPartitioner;
 
 /**
- * Channels of Buffer It contais all buffer data which belongs to this channel. It supports several strategy when buffer
+ * Channels of Buffer It contains all buffer data which belongs to this channel. It supports several strategy when buffer
  * is full. The Default is BLOCKING <p> Created by wusheng on 2016/10/25.
  */
 public class Channels<T> {

apm-sniffer/apm-sdk-plugin/mysql-5.x-plugin/src/main/java/org/apache/skywalking/apm/plugin/jdbc/mysql/v5/define/Mysql50ConnectionInstrumentation.java

@@ -24,7 +24,7 @@ import org.apache.skywalking.apm.agent.core.plugin.match.ClassMatch;
 import static org.apache.skywalking.apm.agent.core.plugin.match.NameMatch.byName;
 
 /**
- * {@link Mysql50ConnectionInstrumentation} interceptor the com.mysql.jdbc.Connection class in the 5.0.x verison
+ * {@link Mysql50ConnectionInstrumentation} interceptor the com.mysql.jdbc.Connection class in the 5.0.x version
  * of mysql driver jar.
  *
  * @author zhangxin

docs/powered-by.md

@@ -94,7 +94,7 @@ Integrated in the microservices architecture support platform.
 Use SkyWalking and [SkyAPM .net agent](https://github.com/SkyAPM/SkyAPM-dotnet) in the CMBChina Mall project.
 
 ## ke.com
-Deploy SkyWalking in production enviroments. 
+Deploy SkyWalking in production environments.
 - Three CentOs Machines(32 CPUs, 64G RAM, 1.3T Disk) for Collector Server
 - Three ElasticSearch(Version 6.4.2, 40 CPUs, 96G RAM, 7T Disk) Nodes for Storage