[Doc] Update ChatQnA README for Nginx Docker Image (opea-project#862)

Signed-off-by: letonghan <letong.han@intel.com>

Author: letonghan

ChatQnA/README.md

@@ -72,7 +72,7 @@ docker pull opea/chatqna-ui:latest
 
 In following cases, you could build docker image from source by yourself.
 
-- Failed to download the docker image. (The essential Docker image `opea/nginx` has not yet been released, users need to build this image first)
+- Failed to download the docker image.
 
 - If you want to use a specific version of Docker image.
 

ChatQnA/docker_compose/intel/cpu/xeon/README.md

@@ -49,7 +49,7 @@ docker pull opea/chatqna-ui:latest
 
 In following cases, you could build docker image from source by yourself.
 
-- Failed to download the docker image. (The essential Docker image `opea/nginx` has not yet been released, users need to build this image first)
+- Failed to download the docker image.
 
 - If you want to use a specific version of Docker image.
 

ChatQnA/docker_compose/intel/hpu/gaudi/README.md

@@ -50,7 +50,7 @@ docker pull opea/chatqna-ui:latest
 
 In following cases, you could build docker image from source by yourself.
 
-- Failed to download the docker image. (The essential Docker image `opea/nginx` has not yet been released, users need to build this image first)
+- Failed to download the docker image.
 
 - If you want to use a specific version of Docker image.
 

ChatQnA/docker_compose/nvidia/gpu/README.md

@@ -50,7 +50,7 @@ docker pull opea/chatqna-ui:latest
 
 In following cases, you could build docker image from source by yourself.
 
-- Failed to download the docker image. (The essential Docker image `opea/nginx` has not yet been released, users need to build this image first)
+- Failed to download the docker image.
 
 - If you want to use a specific version of Docker image.