Added missing logos

Signed-off-by: Taras Mankovski <taras@frontside.com>

microsite/data/plugins/gke-usage.yaml

@@ -5,7 +5,7 @@ authorUrl: https://bestsellerit.com
 category: Discovery
 description: This plugin will show you the cost and resource usage of your application within Google Kubernetes Engine (GKE).
 documentation: https://github.com/BESTSELLER/backstage-plugin-gkeusage/blob/master/README.md
-iconUrl: https://bestsellerit.com/img/google-container-engine_avatar.svg
+iconUrl: img/gke-logo.png
 npmPackageName: '@bestsellerit/backstage-plugin-gkeusage'
 tags:
   - gke

microsite/data/plugins/harbor.yaml

@@ -5,7 +5,7 @@ authorUrl: https://bestsellerit.com
 category: Discovery
 description: This plugin will show you information about Docker images within the Harbor cloud native registry.
 documentation: https://github.com/BESTSELLER/backstage-plugin-harbor/blob/master/README.md
-iconUrl: https://bestsellerit.com/img/terraform-harbor/goharbor.jpeg
+iconUrl: img/harbor-logo.png
 npmPackageName: '@bestsellerit/backstage-plugin-harbor'
 tags:
   - goharbor

microsite/data/plugins/humanitec.yaml

@@ -7,5 +7,5 @@ description: |
   Show workloads, environments and resources deployed by Humanitec Platform Orchestrator. 
   Plugin includes an Entity ComponentCard, Backend API route and scaffolder actions.
 documentation: https://github.com/thefrontside/backstage/tree/main/plugins/humanitec
-iconUrl: ../../static/img/humanitec-logo.png
+iconUrl: img/humanitec-logo.png
 npmPackageName: '@frontside/backstage-plugin-humanitec'