Updated docs because of meadow deprecations

[sgiorgetti]

Use case

We have deprecated eHive support for some job scheduler, and consequently eHive meadows.
Docs need updating to reflect these changes.

Possible Drawbacks

None

Testing

N/A

[sgiorgetti]

@TamaraNaboulsi - would you mind to have a look at this?
The majority of examples in the entire doc set is based on LSF for historical reasons.
TBH, I applied minimum changes and unsure if adequate - especially on docs/running_pipelines/management.rst.
Does it make sense? Pls, comment and criticise at will. Thanks

[EbiArnie]

Definitely and improvement over the status quo.
OK from my side.

[TamaraNaboulsi]

Very much needed docs update now that SLURM is the default rather than LSF. Changes look good and are very descriptive.
Concerning "management.rst", it does still contain multiple mentions of LSF. However, these mentions are used in examples of hive operations (like beekeeper output) and thus the actual information there doesn't change whether it is LSF or SLURM. It would be nice to change these later on just so the operations of the users look like the examples here, but it's not super important for now.