docs(agent): Specify jitter value must be non-zero

fixes: influxdata#15227

docs/CONFIGURATION.md

@@ -391,12 +391,12 @@ Parameters that can be used with any input plugin:
 - **collection_jitter**:
  Overrides the `collection_jitter` setting of the [agent][Agent] for the
  plugin. Collection jitter is used to jitter the collection by a random
- [interval][].
+ [interval][]. The value must be non-zero to override the agent setting.
 
 - **collection_offset**:
  Overrides the `collection_offset` setting of the [agent][Agent] for the
  plugin. Collection offset is used to shift the collection by the given
- [interval][].
+ [interval][]. The value must be non-zero to override the agent setting.
 
 - **name_override**: Override the base name of the measurement. (Default is
  the name of the input).
@@ -481,7 +481,8 @@ Parameters that can be used with any output plugin:
 - **flush_interval**: The maximum time between flushes. Use this setting to
  override the agent `flush_interval` on a per plugin basis.
 - **flush_jitter**: The amount of time to jitter the flush interval. Use this
- setting to override the agent `flush_jitter` on a per plugin basis.
+ setting to override the agent `flush_jitter` on a per plugin basis. The value
+ must be non-zero to override the agent setting.
 - **metric_batch_size**: The maximum number of metrics to send at once. Use
  this setting to override the agent `metric_batch_size` on a per plugin basis.
 - **metric_buffer_limit**: The maximum number of unsent metrics to buffer.