Update docs for redis (grafana#2728)

Signed-off-by: Cyril Tovena <cyril.tovena@gmail.com>

docs/sources/configuration/_index.md

@@ -1408,10 +1408,15 @@ memcached_client:
   [consistent_hash: <bool>]
 
 redis:
-  # Redis service endpoint to use when caching chunks. If empty, no redis will be used.
+  # Redis Server endpoint to use for caching. A comma-separated list of endpoints
+  # for Redis Cluster or Redis Sentinel. If empty, no redis will be used.
   # CLI flag: -<prefix>.redis.endpoint
   [endpoint: <string>]
 
+  # Redis Sentinel master name. An empty string for Redis Server or Redis Cluster.
+  # CLI flag: -<prefix>.redis.master-name
+  [master_name: <string>]
+
   # Maximum time to wait before giving up on redis requests.
   # CLI flag: -<prefix>.redis.timeout
   [timeout: <duration> | default = 100ms]
@@ -1420,13 +1425,13 @@ redis:
   # CLI flag: -<prefix>.redis.expiration
   [expiration: <duration> | default = 0s]
 
-  # Maximum number of idle connections in pool.
-  # CLI flag: -<prefix>.redis.max-idle-conns
-  [max_idle_conns: <int> | default = 80]
+  # Database index.
+  # CLI flag: -<prefix>.redis.db
+  [db: <int>]
 
-  # Maximum number of active connections in pool.
-  # CLI flag: -<prefix>.redis.max-active-conns
-  [max_active_conns: <int> | default = 0]
+  # Maximum number of connections in the pool.
+  # CLI flag: -<prefix>.redis.pool-size
+  [pool_size: <int> | default = 0]
 
   # Password to use when connecting to redis.
   # CLI flag: -<prefix>.redis.password
@@ -1436,6 +1441,16 @@ redis:
   # CLI flag: -<prefix>.redis.enable-tls
   [enable_tls: <boolean> | default = false]
 
+  # Close connections after remaining idle for this duration.
+  # If the value is zero, then idle connections are not closed.
+  # CLI flag: -<prefix>.redis.idle-timeout
+  [idle_timeout: <duration> | default = 0s]
+
+  # Close connections older than this duration. If the value is zero, then
+  # the pool does not close connections based on age.
+  # CLI flag: -<prefix>.redis.max-connection-age
+  [max_connection_age: <duration> | default = 0s]
+
 fifocache:
   # Maximum memory size of the cache in bytes. A unit suffix (KB, MB, GB) may be
   # applied.