Fix TCP keepalive configuration (#77)

Fix key name inconsistency: the inner guard checked
"tcpKeepalives" (plural) while the value rendered
`.Values.tcpKeepalive` (singular), causing `keepalive = <no value>` when
`tcpKeepalives` was set.  Standardize on singular to match Linux
convention (`SO_KEEPALIVE`, `tcp_keepalive_time`) and the pgdog TOML
key.

Also fix commented-out defaults in `values.yaml` and `README.md`:
`tcpTime` and `tcpInterval` were in seconds (Linux kernel defaults) but
pgdog expects milliseconds.

Author: NJAldwin

README.md

@@ -255,13 +255,14 @@ Configure socket-level TCP keep-alive behavior (optional):
 
 ```yaml
 tcpKeepalive: true
-tcpTime: 7200 # Time (in seconds) before first keepalive probe
-tcpInterval: 75 # Interval (in seconds) between keepalive probes
+tcpTime: 7200000 # 2 hours (ms) before first keepalive probe
+tcpInterval: 75000 # 75 seconds (ms) between keepalive probes
 tcpRetries: 9 # Number of keepalive probes before connection is dropped
 ```
 
 These settings control the TCP keep-alive behavior for database
-connections. If not specified, system defaults are used.
+connections. All time values are in milliseconds. If not specified,
+system defaults are used.
 
 ## Contributions
 

templates/config.yaml

@@ -239,7 +239,7 @@ data:
 
         {{- if or (hasKey .Values "tcpKeepalive") (hasKey .Values "tcpTime") (hasKey .Values "tcpInterval") (hasKey .Values "tcpRetries") }}
         [tcp]
-        {{- if hasKey .Values "tcpKeepalives" }}
+        {{- if hasKey .Values "tcpKeepalive" }}
         keepalive = {{ .Values.tcpKeepalive }}
         {{- end }}
         {{- if hasKey .Values "tcpTime" }}

values.yaml

@@ -470,10 +470,11 @@ control:
 # lsnCheckInterval: 1000  # How frequently to re-fetch replication status
 
 # TCP keep-alive configuration (optional)
-# These settings control socket-level keep-alive behavior
-# tcpKeepalives: true
-# tcpTime: 7200
-# tcpInterval: 75
+# These settings control socket-level keep-alive behavior.
+# All time values are in milliseconds.
+# tcpKeepalive: true
+# tcpTime: 7200000     # 2 hours (Linux default: 7200s)
+# tcpInterval: 75000   # 75 seconds (Linux default: 75s)
 # tcpRetries: 9
 
 # Memory configuration (optional)