Fix shell command in README

[ilkimo]

If applied, this commit will correct the yq command to extract the public key from the secret.

Changes done:

• fix the $ yq .stringData key path
• remove the "| base64 --decode" as the key is not encoded when generated by the $ flux create secret git command
• use the proper path to the file according to the previous command in the README step-by-step explanation

The proper use of the $ yq command can also be verified directly in the official help section $ flux create secret git --help
Launch it and search for "yq" to jump directly to the --help example.

[matheuscscp]

@stefanprodan The workflow is not getting triggered 🤔 I'm also not seeing it in the files. Should this requirement be removed from the settings?

[stefanprodan]

@matheuscscp that e2e workflow is for own branches, not PRs from forks, we could remove the requirement.