chore: move install docs into seperate install section and setting up cluster to admin section

docs/administration/setting-up-your-cluster/README.md

@@ -1,7 +1,7 @@
 ---
 title: "Setting Up Your Cluster"
 description: "Import an AMI, create a VPC with a public subnet, and launch your first EC2 instance on Spinifex."
-category: "Getting Started"
+category: "Administration"
 tags:
   - setup
   - vpc

docs/install/install-airgapped/README.md

@@ -1,7 +1,7 @@
 ---
 title: "Air-Gapped Install"
 description: "Deploy Spinifex in environments without internet connectivity. Covers using a pre-built release tarball, mirrored APT packages, and locally-staged cloud images."
-category: "Getting Started"
+category: "Install"
 tags:
   - install
   - air-gapped

docs/install/install-multi-node/README.md

@@ -1,7 +1,7 @@
 ---
 title: "Multi-Node Install"
 description: "Deploy Spinifex across multiple servers to create an availability zone with high availability, data durability, and fault tolerance."
-category: "Getting Started"
+category: "Install"
 tags:
   - install
   - multi node

docs/install/install-source/README.md

@@ -1,7 +1,7 @@
 ---
 title: "Source Install"
 description: "Build Spinifex from source for development, custom builds, or contributing."
-category: "Getting Started"
+category: "Install"
 tags:
   - install
   - source

docs/install/install-usb/README.md

@@ -1,7 +1,7 @@
 ---
 title: "Bootable USB Install"
 description: "Install Spinifex on bare-metal hardware by flashing the Spinifex ISO to a USB drive and booting the target device from it."
-category: "Getting Started"
+category: "Install"
 sections:
   - overview
   - troubleshooting

docs/install/install/README.md

@@ -1,7 +1,7 @@
 ---
 title: "Single-Node Install"
 description: "Install Spinifex on a single server using the binary installer."
-category: "Getting Started"
+category: "Install"
 tags:
   - install
   - single node