document new parameters

docs/mkdocs/configuration.md

@@ -21,6 +21,9 @@ An ebtel++ run is configured by a single XML configuration file. The table below
 | **c1_rad0** | `float` | Nominal value of $c_1$ during radiative phase; see Eq. 16 of [Cargill et al. (2012a)][cargill_2012a] |
 | **helium_to_hydrogen_ratio** | `float` | Ratio of helium to hydrogen abundance; used in correction to ion mass, ion equation of state |
 | **surface_gravity** | `float` | Surface gravity in units of solar surface gravity; should be set to 1.0 unless using for extra-solar cases |
+| **loop_length_ratio_tr_total** | `float` | Ratio between the length of the TR and the total loop length. Typically, a value of 0.15 is used. |
+| **area_ratio_tr_corona** | `float` | Ratio between the cross-sectional area averaged over the transition region and averaged over the corona |
+| **area_ratio_0_corona** | `float` | Ratio between the cross-sectional area at the TR-corona boundary and the cross-sectional area averaged over the corona |
 
 ### Heating
 The time dependent heating is configured in a separate node. It includes the following parameters,