Rename assembler environment from production to prod (#798)

* Rename assembler environment from `production` to `prod`

To align with infrastructure naming

* Fix test

Author: reakaleek

src/docs-assembler/assembler.yml

@@ -1,5 +1,5 @@
 environments:
-  production:
+  prod:
     uri: https://www.elastic.co
     path_prefix: docs
     allow_indexing: false
@@ -86,4 +86,4 @@ references:
     skip: true
   security-docs:
     # wait for move to https://github.com/elastic/detection-rules/pull/4507/files
-    skip: true
+    skip: true

tests/docs-assembler.Tests/src/docs-assembler.Tests/GlobalNavigationTests.cs

@@ -51,7 +51,7 @@ public async Task UriResolving()
 		var checkouts = repos.Select(r => CreateCheckout(fs, r)).ToArray();
 		var globalNavigation = new GlobalNavigation(assembleContext, globalNavigationFile, checkouts);
 
-		var env = assembleContext.Configuration.Environments["production"];
+		var env = assembleContext.Configuration.Environments["prod"];
 		var uriResolver = new PublishEnvironmentUriResolver(globalNavigation, env);
 
 		// docs-content://reference/apm/something.md - url hasn't changed