Add the newly mapped signals and link sources to their doc pages

Author: capnrefsmmat

docs/api/covidcast_signals.md

@@ -23,12 +23,14 @@ map](https://covidcast.cmu.edu/):
 
 | Name | Source | Signal |
 | --- | --- | --- |
-| Doctor's Visits | `doctor-visits` | `smoothed_adj_cli` |
-| Symptoms (Facebook) | `fb-survey` | `smoothed_cli` |
-| Symptoms in Community (Facebook) | `fb-survey` | `smoothed_hh_cmnty_cli` |
-| Search Trends (Google) | `ght` | `smoothed_search` |
-| Combined | `indicator-combination` | `nmf_day_doc_fbc_fbs_ght` |
-| Cases | `jhu-csse` | `confirmed_incidence_num` |
-| Cases per capita | `jhu-csse` | `confirmed_incidence_prop` |
-| Deaths | `jhu-csse` | `deaths_incidence_num` |
-| Deaths per capita | `jhu-csse` | `confirmed_incidence_prop` |
+| Doctor's Visits | [`doctor-visits`](covidcast-signals/doctor-visits.md) | `smoothed_adj_cli` |
+| Symptoms (Facebook) | [`fb-survey`](covidcast-signals/fb-survey.md) | `smoothed_cli` |
+| Symptoms in Community (Facebook) | [`fb-survey`](covidcast-signals/fb-survey.md) | `smoothed_hh_cmnty_cli` |
+| Away from Home 6hr+ (SafeGraph) | [`safegraph`](covidcast-signals/safegraph.md) | `full_time_work_prop` |
+| Away from Home 3-6hr (SafeGraph) | [`safegraph`](covidcast-signals/safegraph.md) | `part_time_work_prop` |
+| Search Trends (Google) | [`ght`](covidcast-signals/ght.md) | `smoothed_search` |
+| Combined | [`indicator-combination`](covidcast-signals/indicator-combination.md) | `nmf_day_doc_fbc_fbs_ght` |
+| Cases | [`jhu-csse`](covidcast-signals/jhu-csse.md) | `confirmed_incidence_num` |
+| Cases per capita | [`jhu-csse`](covidcast-signals/jhu-csse.md) | `confirmed_incidence_prop` |
+| Deaths | [`jhu-csse`](covidcast-signals/jhu-csse.md) | `deaths_incidence_num` |
+| Deaths per capita | [`jhu-csse`](covidcast-signals/jhu-csse.md) | `confirmed_incidence_prop` |