docs: update groups spec & cli instructions (#11516)

## Description

Fixes group spec and CLI instructions that were still using timeout instead of voting_period

### Author Checklist

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I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/master/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/master/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

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- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

x/group/client/cli/tx.go

@@ -290,7 +290,8 @@ If group-policy-as-admin flag is set to true, the admin of the newly created gro
 
 Example:
 $ %s tx group create-group-with-policy [admin] [group-metadata] [group-policy-metadata] [members-json-file] \
-'{"@type":"/cosmos.group.v1.ThresholdDecisionPolicy", "threshold":"1", "timeout":"1s"}'
+'{"@type":"/cosmos.group.v1.ThresholdDecisionPolicy", "threshold":"1", \
+"windows": {"voting_period": "120h", "min_execution_period": "0s"}}'
 
 where members.json contains:
 
@@ -378,10 +379,11 @@ Note, the '--from' flag is ignored as it is implied from [admin].
 
 Example:
 $ %s tx group create-group-policy [admin] [group-id] [metadata] \
-'{"@type":"/cosmos.group.v1.ThresholdDecisionPolicy", "threshold":"1", "timeout":"1s"}'
+'{"@type":"/cosmos.group.v1.ThresholdDecisionPolicy", "threshold":"1", \
+"windows": {"voting_period": "120h", "min_execution_period": "0s"}}'
 
 Here, we can use percentage decision policy when needed, where 0 < percentage <= 1.
-Ex: '{"@type":"/cosmos.group.v1.PercentageDecisionPolicy", "percentage":"0.5", "timeout":"1s"}'
+Ex: '{"@type":"/cosmos.group.v1.PercentageDecisionPolicy", "percentage":"0.5", "windows": {"voting_period": "120h", "min_execution_period": "0s"}}
 `,
 				version.AppName,
 			),
@@ -560,7 +562,7 @@ Parameters:
 			msg_tx_json_file: path to json file with messages that will be executed if the proposal is accepted.
 
 Example:
-	$ %s tx gov submit-proposal path/to/proposal.json
+	$ %s tx group submit-proposal path/to/proposal.json
 	
 	Where proposal.json contains: