Fully specify urls for repo files in VSCE README

[adam-wolfe]

What It Does Addresses https://github.com/zowe/cics-for-zowe-client/issues/155

URLs to resources from this repository have been updated to include the full file path.

How to Test Build and package the extension, and confirm that the URLs to screenshots and other resources work properly.

Review Checklist I certify that I have:

• [x] tested my changes
• [ ] added/updated automated tests
• [ ] updated the changelog
• [ ] followed the contribution guidelines

Additional Comments

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 93.17%. Comparing base (09e8588) to head (ba8f84d). Report is 3 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #156 +/- ## ======================================= Coverage 93.17% 93.17% ======================================= Files 73 73 Lines 718 718 Branches 54 55 +1 ======================================= Hits 669 669 Misses 49 49 ```

:umbrella: View full report in Codecov by Sentry.
:loudspeaker: Have feedback on the report? Share it here.

[github-actions[bot]]

Release succeeded for the main branch with some errors. :warning:

The following packages have been published:

• vsce: Zowe.cics-extension-for-zowe@3.0.1
• vsce: ❌ Zowe.cics-extension-for-zowe@3.0.1 (OVSX)

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