Add Details About tenv Lockfiles to the documentation

[kvendingoldo]

Describe the solution you'd like
Enhance the documentation by including information about how tenv handles lockfiles, particularly when multiple instances are run in parallel. Currently, it is unclear whether tenv fails outright if the lock is already taken or if it waits for the lock to be released. Providing clarity on this behavior will help users understand the expected behavior in such scenarios and avoid potential confusion or misconfigurations.

Additional context
Link to slack discussion: https://opentofucommunity.slack.com/archives/C05R0FD0VRU/p1734253608366379