enable input metrics (#578)

Signed-off-by: Shizuo Fujita <[email protected]>

Author: Watson1978

deployment/command-line-option.md

@@ -37,7 +37,8 @@ Usage: fluentd [options]
         --use-v1-config              Use v1 configuration format (default)
         --use-v0-config              Use v0 configuration format
         --strict-config-value        Parse config values strictly
-        --enable-input-metrics       Enable input plugin metrics on fluentd
+        --enable-input-metrics       [DEPRECATED] Enable input plugin metrics on fluentd
+        --disable-input-metrics      Disable input plugin metrics on fluentd
         --enable-size-metrics        Enable plugin record size metrics on fluentd
     -v, --verbose                    increase verbose level (-v: debug, -vv: trace)
     -q, --quiet                      decrease verbose level (-q: warn, -qq: error)

deployment/system-config.md

@@ -202,9 +202,9 @@ Enable JIT for worker processes. Internally, this configuration enables Ruby's `
 
 | type | default | version |
 | :--- | :---    | :---    |
-| bool | nil     | 1.14.0  |
+| bool | true    | 1.14.0  |
 
-Specifies whether measuring input metrics should be enabled or not.
+Specifies whether measuring input metrics should be enabled or not. Since v1.19.0, the default value is changed to `true`.
 
 ### `enable_size_metrics`