Polish GJ example readme (#1726)

example/gap_junctions/gap_junctions.cpp

@@ -315,7 +315,7 @@ arb::cable_cell gj_cell(cell_gid_type gid, unsigned ncell, double stim_duration)
     decor.place(arb::mlocation{0, 1}, arb::gap_junction_site{}, "local_0");
     decor.place(arb::mlocation{0, 1}, arb::gap_junction_site{}, "local_1");
 
-    // Attach a stimulus to the second cell.
+    // Attach a stimulus to the first cell of the first group
     if (!gid) {
         auto stim = arb::i_clamp::box(0, stim_duration, 0.4);
         decor.place(arb::mlocation{0, 0.5}, stim, "stim");

example/gap_junctions/readme.md

 # Gap Junctions Example
+A miniapp that demonstrates how to build a network with gap junctions.
 
-A miniapp that demonstrates how to describe how to build a network with gap junctions.
+## Cells
+Cells have a simple ball-and-stick morphology with gap junctions attached at the
+end of the soma. The following mechanisms are assigned to the complete cell
 
-##Structure:
-Cells are structured into groups that are inter-connected by gap junctions; Groups are
-connected by synapses. The first cell of the first group (top left in diagram) has a 
-current stimulus.
+- `nax`: `gbar=0.04`, `sh=10`
+- `gbar`: `gbar=0.0001`
+- `kamt`: `gbar=0.004`
+- `pas`: `e=-65 mV`, `g=1/12000`
 
+```
+Soma (A=500π µm^2)
+
+ /\\\\\\\
+(  ))))))) ()=================) Dendrite (l=300 µm, r=1.5 µm)
+ \///////
+        * 
+        GJ
+```
+
+## Network
+Cells are structured into groups ('cables') that are inter-connected by gap
+junctions; Groups are connected by synapses. The first cell of the first group
+(top left in diagram) has a current stimulus.
 
 ```
-c --gj-- c --gj-- c --gj-- c --gj-- c
-                                    |
-                                    syn
-                                    |
-c --gj-- c --gj-- c --gj-- c --gj-- c
-|
-syn
-|
-c --gj-- c --gj-- c --gj-- c --gj-- c
+     c --gj-- c --gj-- c --gj-- c --gj-- c   # Cable 0
+     ^                                   |
+    I_s                                 syn
+                                         |
+     c --gj-- c --gj-- c --gj-- c --gj-- c   # Cable 1
+     |
+    syn
+     |
+     c --gj-- c --gj-- c --gj-- c --gj-- c   # Cable 2
+                                         |
+                                        ...
 ```
      
-
 ## Tunable parameters
 * _n_cables_: number of groups of cells connected by gap junctions.
 * _n_cells_per_cable_: number of cells in a group.
@@ -42,4 +60,4 @@ An example parameter file is:
     "sim-duration": 100, 
     "print-all": false
 }
-```
\ No newline at end of file
+```