Rename collection links to directory names (#6040)

Signed-off-by: Fanit Kolchina <kolchfa@amazon.com>

_im-plugin/index.md

@@ -4,14 +4,11 @@ title: Managing indexes
 nav_order: 1
 has_children: false
 nav_exclude: true
-permalink: /index-management/
+permalink: /im-plugin/
 redirect_from:
-  - /im-plugin/
   - /opensearch/index-data/
   - /opensearch/rest-api/index-apis/index/
-  - /index-management/index/
   - /im-plugin/index/
-  - /index-management/
 ---
 
 # Managing indexes

_ml-commons-plugin/index.md

@@ -5,12 +5,9 @@ nav_order: 1
 has_children: false
 has_toc: false
 nav_exclude: true
-permalink: /machine-learning/
+permalink: /ml-commons-plugin/
 redirect_from: 
-  - /ml-commons-plugin/
   - /ml-commons-plugin/index/
-  - /machine-learning/index/
-  - /machine-learning/
 ---
 
 # Machine learning

_observing-your-data/index.md

@@ -4,13 +4,10 @@ title: Observability
 nav_order: 1
 has_children: true
 nav_exclude: true
-permalink: /observability/
+permalink: /observing-your-data/
 redirect_from:
   - /observability-plugin/index/
-  - /observing-your-data/
   - /observing-your-data/index/
-  - /observability/index/
-  - /observability/
 ---
 
 # Observability

_search-plugins/index.md

@@ -5,12 +5,9 @@ nav_order: 1
 has_children: false
 has_toc: false
 nav_exclude: true
-permalink: /search/
+permalink: /search-plugins/
 redirect_from:
-  - /search-plugins/
   - /search-plugins/index/
-  - /search/index/
-  - /search/
 ---
 
 # Search