Fix incorrect bazel version 6.4.0+ in documenation

[blizzardc0der]

Description

The documentation says it supports Bazel 6.4.0+, but the project actually supports bazel 7.0.2+.
I think the documentation needs to be updated.

Here's the bazel version talking in the documenation.

nativelink/README.md

Line 114 in 646253d

* Bazel 6.4.0+

Here's the actual bazel version supported from the .bazelversion file.

nativelink/.bazelversion

Line 1 in 646253d

7.0.2

Fixes #800

Type of change

• Bug fix (non-breaking change which fixes an issue)
• This change requires a documentation update

Checklist

• Updated documentation if needed
• bazel test //... passes locally
• PR is contained in a single commit, using git amend see some docs

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This change is 

[blizzardc0der]

I hope you to review this. cc: @allada, @steed924 .

[adam-singer]

Reviewed 1 of 1 files at r1, all commit messages.
Reviewable status: 1 of 1 LGTMs obtained, and pending CI: Bazel Dev / ubuntu-22.04, Cargo Dev / macos-13, docker-compose-compiles-nativelink (20.04), docker-compose-compiles-nativelink (22.04), macos-13, windows-2022 / stable, zig-cc ubuntu-20.04, zig-cc ubuntu-22.04

[aaronmondal]

Thanks!

Reviewed all commit messages.
Reviewable status: complete! 2 of 1 LGTMs obtained