Fix documentation inconsistencies and remove dead options

[superworm]

Fix documentation inconsistencies and remove dead options

This PR addresses several documentation inconsistencies and removes a dead option across the utilities:

1. Correct Multiload Sample Duration:
   • Updated multiload help text and README to correctly state the sample duration is 2.0 seconds (matching LOAD_DELAY_RUN_uS which is set to 2,000,000 us), rather than the incorrect 0.5 seconds.
2. Remove Dead -S Option:
   • Removed S: from the getopt string in both multichase.c and multiload.c. The option was accepted by getopt but had no corresponding case in the switch statement, leading to silent failures/fallthroughs to usage help.
3. Document Supported Options:
   • Added the supported -v (verbosity) option to the multichase help message.
   • Added the supported -S (separator) option to the fairness usage and help description.