fix: delete ru docs

[fedekunze]

Description

Closes: #XXXX

Deleted the ru docs (unmaintained) because of name collision

make install                                            
echo "Ensure dependencies have not been modified ..." >&2
Ensure dependencies have not been modified ...
go mod verify
go: github.com/cosmos/cosmos-sdk@v0.44.3 (replaced by github.com/tharsis/cosmos-sdk@v0.44.3-evmos): verifying go.mod: github.com/tharsis/cosmos-sdk@v0.44.3-evmos/go.mod: reading https://sum.golang.org/lookup/github.com/tharsis/cosmos-sdk@v0.44.3-evmos: 410 Gone
	server response: not found: create zip: docs/ru/readme.md: case-insensitive file name collision: "docs/ru/README.md" and "docs/ru/readme.md"
make: *** [go.sum] Error 1

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Author Checklist

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I have...

• included the correct type prefix in the PR title
• added ! to the type prefix if API or client breaking change
• targeted the correct branch (see PR Targeting)
• provided a link to the relevant issue or specification
• followed the guidelines for building modules
• included the necessary unit and integration tests
• added a changelog entry to CHANGELOG.md
• included comments for documenting Go code
• updated the relevant documentation or specification
• reviewed "Files changed" and left comments if necessary
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• confirmed the correct type prefix in the PR title
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• reviewed state machine logic
• reviewed API design and naming
• reviewed documentation is accurate
• reviewed tests and test coverage
• manually tested (if applicable)