docs(marketplace): use image URLs (again)

Problem:
vsce package always replaces .gif image paths with URLs. For example,
    ![creds](./resources/marketplace/vscode/creds.gif)
is replaced with:
    ![creds](https://github.com/aws/aws-toolkit-vscode/raw/HEAD/resources/marketplace/vscode/creds.gif)
This only happens for .gif, not .png.
Furthermore, both GitLens and CoPilot (two major vscode extensions) use
URLs for their README.md gifs.
Example: from `GitHub.copilot-1.78.9758.vsix`:
    ![comment-to-code](https://user-images.githubusercontent.com/37570492/212965036-26579d9f-cfaf-44eb-90fb-76421dc7ab9d.gif)
Example: from GitLens https://raw.githubusercontent.com/gitkraken/vscode-gitlens/main/README.md

Solution:
Use URLs for .gif images.

Author: justinmk3

README.quickstart.vscode.md

@@ -14,57 +14,57 @@ The AWS Toolkit lets you interact with AWS directly from VS Code. Ready to insta
 
 Access AWS resources across your accounts and regions.
 
-![creds](./resources/marketplace/vscode/creds.gif)
+![creds](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/creds.gif)
 
 ### S3 support
 
 View, create, and edit S3 buckets, folders, and files.
 
-![S3](./resources/marketplace/vscode/S3.gif)
+![S3](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/S3.gif)
 
 ### Download & upload Lambda functions
 
-![download-Lambda](./resources/marketplace/vscode/download-Lambda.gif)
+![download-Lambda](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/download-Lambda.gif)
 
 ## Troubleshoot AWS from the IDE
 
 ### Lambda
 
 Step-through AWS Lambda functions using the VS Code debugger
 
-![Lambda_step_through_debugging](./resources/marketplace/vscode/Lambda_step_through_debugging.gif)
+![Lambda_step_through_debugging](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/Lambda_step_through_debugging.gif)
 
 ### CloudWatch Logs
 
 Find logs generated by your AWS resources
 
-![cw_logs](./resources/marketplace/vscode/cw_logs.gif)
+![cw_logs](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/cw_logs.gif)
 
 ### ECS
 
 Execute commands against running ECS containers (or open a terminal)
 
-![ecs-terminal](./resources/marketplace/vscode/ecs-terminal.gif)
+![ecs-terminal](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/ecs-terminal.gif)
 
 ## Write and edit code faster
 
 ### [Amazon CodeWhisperer](https://aws.amazon.com/codewhisperer/)
 
 Build applications faster with automatic code recommendations based on the code and comments in VS Code.
 
-![CodeWhisperer](./resources/marketplace/vscode/codewhisperer.gif)
+![CodeWhisperer](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/codewhisperer.gif)
 
 ### [Amazon CodeCatalyst](https://aws.amazon.com/codecatalyst/)
 
 Launch VS Code in a cloud development environment, powered by Amazon CodeCatalyst.
 
-![CodeCatalyst](./resources/marketplace/vscode/CC_dev_env.gif)
+![CodeCatalyst](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/CC_dev_env.gif)
 
 ### CloudFormation
 
 Autocompletion and syntax support for CloudFormation templates
 
-![cfn_autocompletion](./resources/marketplace/vscode/cfn_autocompletion.gif)
+![cfn_autocompletion](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/cfn_autocompletion.gif)
 
 ## More features
 
@@ -88,7 +88,7 @@ For a full list of features, visit [our documentation](https://docs.aws.amazon.c
     2. **CodeWhisperer** - connect using an AWS Builder ID or IAM Identity Center (formerly SSO)
     3. **CodeCatalyst** - connect using AWS Builder ID
 
-![getting-started](./resources/marketplace/vscode/getting-started.gif)
+![getting-started](https://raw.githubusercontent.com/aws/aws-toolkit-vscode/master/docs/marketplace/vscode/getting-started.gif)
 
 ## Troubleshooting