docs: document labels (#3)

Reviewed-on: #3

README.md

@@ -1,3 +1,25 @@
 # Kubernetes Cluster Configuration
 
 This repository contains Kubernetes node label configurations for cluster management.
+
+## Labeling Convention
+
+All labels use the `de.t000-n.` prefix.
+
+### Network Labels
+
+- `net.class`: Network speed classification
+  - `"fast"`: High-speed network (10 Gigabit)
+  - `"medium"`: Medium-speed network (2.5 Gigabit)
+  - `"slow"`: Lower-speed network (1 Gigabit)
+- `net.bw`: Network bandwidth specification (e.g., "10g", "2.5g", "1g")
+
+### Storage Mount Labels
+
+- `drive.mnt-{name}`: Indicates a mounted drive under `/mnt/{name}`
+  - Example: `drive.mnt-syncthing` → `/mnt/syncthing` is mounted
+
+### System Configuration Labels
+
+- `sysctl.{setting}`: Indicates a sysctl configuration setting
+  - Example: `sysctl.net.ipv4.conf.all.src_valid_mark` → IPv4 source validation mark setting