Fixes for linkx

Signed-off-by: Dj Walker-Morgan <dj.walker-morgan@enterprisedb.com>

Author: djw-m

product_docs/docs/pgd/6/essential-how-to/install/01-prerequisites.mdx

@@ -5,7 +5,7 @@ navTitle: Prerequisites
 
 This guide takes you through the steps to install EDB Postgres Distributed (PGD) Essential on your systems.
 
-If you want to install a learning/test environment, we recommend using the [PGD Essential Quickstart](/pgd/latest/quickstart).
+If you want to install a learning/test environment, we recommend using the [PGD First Cluster](/pgd/latest/get-started/first-cluster).
 
 !!! Note
 If you want to install EDB Postgres Distributed (PGD) Expanded, consult the [Expanded installation guide](/pgd/latest/expanded-how-to/install/01-prerequisites).

product_docs/docs/pgd/6/reference/index.mdx

@@ -15,6 +15,7 @@ navigation:
 - commit-scopes
 - conflict-management
 - testing-tuning
+- upgrades
 - "# Guidance for developers"
 - appusage
 - "# Advanced functionality"
@@ -49,6 +50,7 @@ The PGD Reference section provides detailed information about PGD's features.
 * [Commit Scopes](/pgd/latest/reference/commit-scopes)
 * [Conflict Management](/pgd/latest/reference/conflict-management)
 * [Testing and Tuning](/pgd/latest/reference/testing-tuning)
+* [Upgrades](/pgd/latest/reference/upgrades)
 
 ## Advanced Functionality
 * [Application Usage](/pgd/latest/reference/appusage)