- Make more clear the docs at docs/enterprise.md, so readers could figure out faster
on how to obtain enterprise key and how to pass it to VictoriaMetrics Enterprise components.
- Fix examples at docs/enterprise.md, which were referring to non-existing `-license-file` command-line flag.
The `-licenseFile` command-line flag must be used instead.
- Improve the description of `-license*` command-line flags, so users could understand
faster how to use them.
- Improve the warning message, which is emitted when the deprecated -eula command-line flag is passed,
so the user could figure out how to switch faster to -license* command-line flags.
- Disallow running VictoriaMetrics components with both -license and -licenseFile command-line flags.
- Disallow running VictoriaMetrics components when -licensFile points to an empty file.
- Consistently use the phrase "This flag is available only in Enterprise binaries" across
all the enterprise-specific command-line flags.
- Remove unneeded level of indirection for `noLicenseMessage` and `expiredMessage` string contants
in order to improve code readability and maintainability.
- Remove unneded `return` statements after `logger.Fatalf()` calls, since these calls exit the app and never return.
- Make sure that the info log message about successful license verification is emitted
when the license is verified successfully. Previously the error message could be logged
when the license payload is invalid or if it misses some required features.
