Update logo image link in README.md

Author: atpolonsky

README.md

@@ -1,6 +1,6 @@
 # pyTriBeam
 
-![main_logo](https://raw.githubusercontent.com/sandialabs/pytribeam/refs/heads/gh-pages/docs/userguide/src/logo_color.png)
+![main_logo](https://raw.githubusercontent.com/sandialabs/pytribeam/refs/heads/gh-pages/docs/userguide/src/logos/logo_color.png)
 
 [![userguide][userguide_badge]](https://sandialabs.github.io/pytribeam/docs/userguide/book/index.html) [![api][api_badge]](https://sandialabs.github.io/pytribeam/docs/api/index.html) [![test-coverage][test-coverage_badge]](https://sandialabs.github.io/pytribeam/coverage_reports/combined/htmlcov/index.html) [![lint][lint_badge]](https://sandialabs.github.io/pytribeam/logs/lint.log) [![version][version_badge]](https://github.com/sandialabs/pytribeam)