Refine FAQ (#6536)

docs/en/FAQ/maven-compile-npm-failure.md

-### Problem： Maven compilation failure with error like `Error: not found: python2`
-When you compile the project via maven, it failed at module `apm-webapp` and the following error occurred.
+### Problem： Maven compilation failure with error such as `Error: not found: python2`
+When you compile the project via Maven, it fails at module `apm-webapp` and the following error occurs.
 
-Pay attention to key words such as `node-sass` and `Error: not found: python2`.
+Pay attention to keywords such as `node-sass` and `Error: not found: python2`.
 
 ```
 [INFO] > node-sass@4.11.0 postinstall C:\XXX\skywalking\skywalking-ui\node_modules\node-sass
@@ -42,11 +42,11 @@ Pay attention to key words such as `node-sass` and `Error: not found: python2`.
 
 ### Reason
 
-It has nothing to do with SkyWalking.   
-According to https://github.com/sass/node-sass/issues/1176, if you live in countries where requesting resources from `GitHub` and `npmjs.org` is very slowly, some precompiled binaries for dependency `node-sass` will fail to be downloaded during `npm install`, then npm will try to compile them itself. That's why `python2` is needed.
+The error has nothing to do with SkyWalking.   
+According to the issue here (https://github.com/sass/node-sass/issues/1176), if you live in countries where requesting resources from `GitHub` and `npmjs.org` runs slow, some precompiled binaries for dependency `node-sass` would fail to be downloaded during `npm install`, and npm would try to compile them itself. That's why `python2` is needed.
 
-### Resolve
-#### 1. Use mirror. Such as in China, please edit `skywalking\apm-webapp\pom.xml`     
+### Resolution
+#### 1. Use mirror. For instance, if you're in China, please edit `skywalking\apm-webapp\pom.xml` as follows.    
 Find
 ```
 <configuration>  
@@ -59,4 +59,4 @@ Replace it with
  <arguments>install --registry=https://registry.npm.taobao.org/ --sass_binary_site=https://npm.taobao.org/mirrors/node-sass/</arguments>  
 </configuration>
 ```
-#### 2. Get an enough powerful VPN
+#### 2. Get a sufficiently powerful VPN.

docs/en/FAQ/thrift-plugin.md

 ### Problem
-The message with Field ID, 8888, must be revered.
+The message with Field ID, 8888, must be reserved.
 
 ### Reason
-Because Thrift cannot carry metadata to transport Trace Header in the original API, we transport those by wrapping TProtocolFactory to do that.
+Because Thrift cannot carry metadata to transport Trace Header in the original API, we transport them by wrapping TProtocolFactory.
 
-Thrift allows us to append any additional field in the Message even if the receiver doesn't deal with them. This data is going to be skipped while no one reads. Base on this, we take the 8888th field of Message to store Trace Header(or metadata) and to transport. That means the message with Field ID, 8888, must be revered.
+Thrift allows us to append any additional fields in the message even if the receiver doesn't deal with them. Those data will be skipped and left unread. Based on this, the 8888th field of the message is used to store Trace Header (or metadata) and to transport them. That means the message with Field ID, 8888, must be reserved.
 
-### Resolve
-Avoiding to use the Field(ID is 8888) in your application.
\ No newline at end of file
+### Resolution
+Avoid using the Field(ID is 8888) in your application.

docs/en/FAQ/v3-version-upgrade.md

@@ -4,8 +4,8 @@
 There is no information showing in the UI.
 
 ### Cause
-In upgrate from 3.2.6 to 5.0.0, Elasticsearch indexes aren't recreated, because not indexes exist, but aren't compatible with 5.0.0-alpha.
-When service name registered, the es will create this column by default type string, which is wrong.
+In the upgrade from version 3.2.6 to 5.0.0, the existing Elasticsearch indexes are kept, but aren't compatible with 5.0.0-alpha.
+When service name is registered, ElasticSearch will create this column by default type string, which will lead to an error.
 
 ### Solution
-Clean the data folder in ElasticSearch and restart ElasticSearch, collector and your under monitoring application.
+Clean the data folder in ElasticSearch and restart ElasticSearch, collector and your application under monitoring.