Merge dev into 5.x for 5.21 release (#209)

* bump dev to 5.21 (#205)

* Replacing underscores with hyphens for crawlability (#206)

---------

Co-authored-by: Jessica Wright <49636617+AlexicaWright@users.noreply.github.com>
Co-authored-by: Lidia Zuin <102308961+lidiazuin@users.noreply.github.com>

antora.yml

@@ -6,10 +6,10 @@ nav:
 - modules/ROOT/content-nav.adoc
 asciidoc:
   attributes:
-    neo4j-version: '5.20'
-    neo4j-version-exact: '5.20.0'
-    neo4j-buildnumber: '5.20'
-    java-driver-version: '5.20.0'
+    neo4j-version: '5.21'
+    neo4j-version-exact: '5.21.0'
+    neo4j-buildnumber: '5.21'
+    java-driver-version: '5.21.0'
     neo4j-documentation-branch: 'dev'
     page-origin-private: false
     neo4j-javadocs-base-uri: "https://neo4j.com/docs/java-reference/5/javadocs"