docs: remove superfluous doc

Refs #656

docs/en/calculators/hyd_en_charge/lechapt-calmon.md

@@ -44,16 +44,3 @@ The correlation table of the coefficients is as follows:
 | Hydraulically smooth pipe - 0.25 ≤ D ≤ 1 | 0.00 | 0.971 | 1.81 | 4.81 |
 
 Table: Materials and coefficients used in the Lechapt and Calmon formula
-
-## Singular head loss
-
-$$ J_S = K_S \frac{V^2}{2g}$$
-
-With:
-
-- \(K_S\) : singular head loss coefficient
-- \(V\) : water speed in the pipe (\(V = 4 Q / \pi / D^2\))
-
-## Darcy's head loss coefficient
-
-$$ f_D = \frac{2g J D}{l_T V^2}