Clarifying GEDI request filters

[scottyhq]

I'm new to GEDI and was initially confused by the formulation of these request parameters (is 0 good or bad :))

parms = {
    "degrade_flag": 0, # 0 -> "not degraded"
    "l2_quality_flag": 1, # 1 -> "good quality"
}

I think this is more an issue with the construction of GEDI metadata, but could be good to add some additional info about possible values of these parameters here
https://slideruleearth.io/web/rtd/user_guide/GEDI.html#parameters.

Looks like this is a good reference to link to https://lpdaac.usgs.gov/documents/982/gedi_l2a_dictionary_P003_v2.html

[scottyhq]

Looks like these changed but docs haven't been updated:

sliderule/docs/rtd/source/release_notes/release-v4-8-0.md

Lines 37 to 42 in f8e233d

	* GEDI parameters updated to be more accurate an intuitive (the old parameter names are still functional but have been DEPRECATED, please switch to using the new ones in your code).
	- `degrade_flag` changed to `degrade_filter` and instead of having to know what the flag values were; the user now just needs to set to True to filter out all degraded footprints.
	- `l2_quality_flag` changed to `l2_quality_filter` and instead of having to know what the flag values were; the user now just needs to set to True to filter out anything that does not meet the L2 quality criteria.
	- `l4_quality_flag` changed to `l4_quality_filter` and instead of having to know what the flag values were; the user now just needs to set to True to filter out anything that does not meet the L4 quality criteria.
	- `surface_flag` changed to `surface_filter` and instead of having to know what the flag values were; the user now just needs to set to True to filter out anything that isn't a surface footprint.
	- `beam` changed to `beams` to reflect that it is primarily a list of beams to process and not just a single beam (even though if the user only provides a single beam, the server side code will automatically promote it to a list of beams with only one element).