Fix incorrect argument name and update description in RNN documentation

[rameshdange5191]

The documentation for the base class for recurrent layers (class RNN exported as keras.layers.RNN) incorrectly mentioned the call argument sequences as inputs. This PR corrects the argument's name in the documentation and updates the argument's description to align more closely with similar arguments in similar layers.

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Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.11%. Comparing base (4895458) to head (4415772).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #20525 +/- ## ======================================= Coverage 82.11% 82.11% ======================================= Files 515 515 Lines 47790 47790 Branches 7486 7486 ======================================= Hits 39242 39242 Misses 6736 6736 Partials 1812 1812 ``` | [Flag](https://app.codecov.io/gh/keras-team/keras/pull/20525/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=keras-team) | Coverage Δ | | |---|---|---| | [keras](https://app.codecov.io/gh/keras-team/keras/pull/20525/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=keras-team) | `81.96% <ø> (ø)` | | | [keras-jax](https://app.codecov.io/gh/keras-team/keras/pull/20525/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=keras-team) | `65.05% <ø> (ø)` | | | [keras-numpy](https://app.codecov.io/gh/keras-team/keras/pull/20525/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=keras-team) | `60.02% <ø> (ø)` | | | [keras-tensorflow](https://app.codecov.io/gh/keras-team/keras/pull/20525/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=keras-team) | `66.03% <ø> (ø)` | | | [keras-torch](https://app.codecov.io/gh/keras-team/keras/pull/20525/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=keras-team) | `64.97% <ø> (ø)` | | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=keras-team#carryforward-flags-in-the-pull-request-comment) to find out more.

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