List the topic subcategories, which can be
used to filter topics within ha_topics().
Examples
# \donttest{
ha_set("chicagohealthatlas.org")
ha_subcategories()
#> # A tibble: 32 × 3
#> subcategory_name subcategory_key category_name
#> <chr> <chr> <chr>
#> 1 Pollution pollution-32 Environmental
#> 2 Access to Care access-to-care Clinical Care
#> 3 Quality of Care quality-of-care Clinical Care
#> 4 Cancer cancer-36 Health Outcomes
#> 5 Community Safety community-safety Physical Environment
#> 6 Housing & Transit housing-transit Physical Environment
#> 7 Pollution pollution-26 Physical Environment
#> 8 Resource Availability resource-availability Physical Environment
#> 9 Behavioral Health behavioral-health-2 Morbidity
#> 10 Chronic Disease chronic-disease-31 Morbidity
#> # ℹ 22 more rows
# }