Update rate language based on feedback.

Author: schnuerle

policy/README.md

@@ -248,7 +248,7 @@ An individual `Rule` object is defined by the following fields:
 | `count` | Fleet counts based on regions. Rule `minimum`/`maximum` refers to number of devices in [Rule Units](#rule-units).                                  |
 | `time`  | Individual limitations on time spent in one or more vehicle-states. Rule `minimum`/`maximum` refers to increments of time in [Rule Units](#rule-units). |
 | `speed` | Global or local speed limits. Rule `minimum`/`maximum` refers to speed in [Rule Units](#rule-units).                  |
-| `rate`  | **[Beta feature](/general-information.md#beta-features):** *Yes (as of 1.0.0)*. Fees or subsidies based on regions and time spent in one or more vehicle-states. Rule `rate_amount` refers to the rate charged according to the [Rate Recurrences](#rate_recurrences) and the [currency requirements](/general-information.md#costs-and-currencies) in [Rule Units](#rule-units). *As this is a beta feature, agencies are strongly advised to consult with providers about how they intended to use the `rate` rule prior to implementation. It is not intended to be changed in real-time without conversations between providers and agencies, and instead is a way to clearly define policy digitally.*    |
+| `rate`  | **[Beta feature](/general-information.md#beta-features):** *Yes (as of 1.0.0)*. Fees or subsidies based on regions and time spent in one or more vehicle-states. Rule `rate_amount` refers to the rate charged according to the [Rate Recurrences](#rate_recurrences) and the [currency requirements](/general-information.md#costs-and-currencies) in [Rule Units](#rule-units). *As this is a beta feature, agencies are strongly advised to consult with providers about how they intended to use the `rate` rule prior to implementation. It is particularly important to communicate in advance how frequently and in what ways rates might change over time.*    |
 | `user`  | Information for users, e.g. about helmet laws. Generally can't be enforced via events and telemetry.          |
 
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