Remove duplicate documentation heading identifiers.

Signed-off-by: Tran Ngoc Nhan <ngocnhan.tran1996@gmail.com>
Closes #3399

src/main/antora/modules/ROOT/pages/dependencies.adoc

@@ -19,7 +19,6 @@ Due to the different inception dates of individual Spring Data modules, most of
 </dependencyManagement>
 ----
 
-[[dependencies.train-names]]
 [[dependencies.train-version]]
 The current release train version is `{releasetrainVersion}`. The train version uses https://calver.org/[calver] with the pattern `YYYY.MINOR.MICRO`.
 The version name follows `+${calver}+` for GA releases and service releases and the following pattern for all other versions: `+${calver}-${modifier}+`, where `modifier` can be one of the following:

src/main/antora/modules/ROOT/pages/repositories/create-instances.adoc

@@ -61,7 +61,7 @@ class ApplicationConfiguration {
 ======
 
 ifeval::[{include-xml-namespaces} != false]
-[[repositories.create-instances.spring]]
+
 [[repositories.create-instances.xml]]
 == XML Configuration
 

src/main/antora/modules/ROOT/pages/upgrade.adoc

@@ -1,4 +1,3 @@
-[[new-features]]
 [[upgrading]]
 = Upgrading Spring Data
 :page-section-summary-toc: 1