Rollup merge of #129594 - lolbinarycat:explain-curl-options, r=albertlarsan68

explain the options bootstrap passes to curl

also fixes a discrepancy where the rust side doesn't use -L

docs are only on the rust side, since duplicated prose has a tendancy to get out-of-sync, and also because there are talks of removing the python script all together eventually.

Author: matthiaskrgr