add documentation for custom_endpoint_ec2

website/source/docs/builders/amazon-chroot.html.md

@@ -278,6 +278,9 @@ each category, the available configuration keys are alphabetized.
     `BuildRegion` variable is replaced with name of the region where this
     is built.
 
+- `custom_endpoint_ec2` (string) - this option is useful if you use 
+    another cloud provider that provide a compatible API with aws EC2,
+    specify another endpoint like this "https://ec2.another.endpoint..com"
 
 ## Basic Example
 

website/source/docs/builders/amazon-ebs.html.md

@@ -334,6 +334,10 @@ builder.
 - `windows_password_timeout` (string) - The timeout for waiting for a Windows
   password for Windows instances. Defaults to 20 minutes. Example value: `10m`
 
+- `custom_endpoint_ec2` (string) - this option is useful if you use 
+    another cloud provider that provide a compatible API with aws EC2,
+    specify another endpoint like this "https://ec2.another.endpoint..com"
+
 ## Basic Example
 
 Here is a basic example. You will need to provide access keys, and may need to

website/source/docs/builders/amazon-ebssurrogate.html.md

@@ -326,6 +326,10 @@ builder.
 - `windows_password_timeout` (string) - The timeout for waiting for a Windows
     password for Windows instances. Defaults to 20 minutes. Example value: `10m`
 
+- `custom_endpoint_ec2` (string) - this option is useful if you use 
+    another cloud provider that provide a compatible API with aws EC2,
+    specify another endpoint like this "https://ec2.another.endpoint..com"
+
 ## Basic Example
 
 ```json

website/source/docs/builders/amazon-ebsvolume.html.md

@@ -226,6 +226,11 @@ builder.
 - `windows_password_timeout` (string) - The timeout for waiting for a Windows
     password for Windows instances. Defaults to 20 minutes. Example value: `10m`
 
+- `custom_endpoint_ec2` (string) - this option is useful if you use 
+    another cloud provider that provide a compatible API with aws EC2,
+    specify another endpoint like this "https://ec2.another.endpoint..com"
+
+
 ## Basic Example
 
 ```json

website/source/docs/builders/amazon-instance.html.md

@@ -336,6 +336,10 @@ builder.
 - `windows_password_timeout` (string) - The timeout for waiting for a Windows
     password for Windows instances. Defaults to 20 minutes. Example value: `10m`
 
+- `custom_endpoint_ec2` (string) - this option is useful if you use 
+    another cloud provider that provide a compatible API with aws EC2,
+    specify another endpoint like this "https://ec2.another.endpoint..com"
+
 ## Basic Example
 
 Here is a basic example. It is completely valid except for the access keys: