update README (#165)

## Purpose
<!-- Describe the intention of the changes being proposed. What problem
does it solve or functionality does it add? -->
* ... Updates Readme doc

## Does this introduce a breaking change?
<!-- Mark one with an "x". -->
```
[ ] Yes
[ x] No
```

## Pull Request Type
What kind of change does this Pull Request introduce?

<!-- Please check the one that applies to this PR using "x". -->
```
[ ] Bugfix
[ ] Feature
[ ] Code style update (formatting, local variables)
[ ] Refactoring (no functional changes, no api changes)
[ x] Documentation content changes
[ ] Other... Please describe:
```

## How to Test
*  Get the code

```
git clone [repo-address]
cd [repo-name]
git checkout [branch-name]
npm install
```

* Test the code
<!-- Add steps to run the tests suite and/or manually test -->
```
```

## What to Check
Verify that the following are valid
* ...

## Other Information
<!-- Add any other helpful information that may be needed here. -->

Author: machavarapun

samples/akri-vscode-extension/sample-rest-server/README.md

@@ -3,7 +3,7 @@
 Run the following commands to build a sample rest server docker image:
 
 ```bash
-    cd preview/akri-connectors-extension/SampleRestServer 
+    cd samples/akri-vscode-extension/sample-rest-server 
     docker build -t rest-server:latest .
 ```