Change nanomaggies to nanomaggy in targeting files

[geordie666]

This PR alters uses of the unit "nanomaggies" to "nanomaggy" in targeting files (after checking that the relevant target-related files do, indeed, use "nanomaggy").

Updates have been made for two reasons:

• Files actually include the formal unit "nanomaggy."
• Or, files include no units, in which case "nanomaggy" is used for consistency.

[coveralls]

Coverage remained the same at 100.0% when pulling 570bdd1 on ADM-nanomag-fix into 84ef041 on main.

[geordie666]

@weaverba137: This should, at least partially, address #129.

Can you tell me which directory you mean when you state to also check the DESI_SURVEY directory in #129? I only touched the DESI_TARGET directory in this PR — although I also checked that the SURVEYOPS directory contains no flux columns that would have maggy-like units.

[weaverba137]

Sure the files in https://github.com/desihub/desidatamodel/tree/main/doc/DESI_SURVEY/fiberassign/SURVEY/TILEXX.

[weaverba137]

DESI_SURVEY=${DESI_ROOT}/survey.

[geordie666]

Thanks — I'm not an expert on the files in DESI_SURVEY, but I'll take a look as part of this PR.

[geordie666]

@weaverba137: I believe I addressed all of the nanomaggies/nanomaggy discrepancies between DESI_TARGET and DESI_SURVEY. This PR is now ready for review.

[weaverba137]

Looks good to me, merge when ready.