Translate doc for blocks concentration

docs-en/calculators/pam/concentration.md

+# Blocks concentration
+
+This module makes it possible to calculate the concentration of uniformly distributed blocks in a rock-ramp fish pass.
+
+It allows to calculate one of the following values:
+
+- The width of the pass (m) ;
+- The number of blocks ;
+- The diameter of the blocks (m) ;
+- The concentration of the blocks \(C\).
+
+## Formula
+
+The formula is detailed in the [rock-ramp fish pass](./macrorugo.md) documentation.
+
+## Harmonization
+
+When calculating the number of blocks, if it is not an integer, upward and downward harmonized numbers of blocks are given along with corresponding concentration values.
+
+Tolerance is of the order of a centimetre.

docs-en/calculators/pam/macrorugo.md

 # Rock-ramp fishpasses
 
-The rock-ramp fishpass calculation module makes it possible to calculate the characteristics of a rock-ramp pass made up of uniformly distributed blocks with equal transverse \(ay\) and longitudinal \(ay\) spacings.
+The rock-ramp fishpass calculation module makes it possible to calculate the characteristics of a rock-ramp pass made up of uniformly distributed blocks with equal transverse \(ax\) and longitudinal \(ay\) spacings.
 
 ![Schematic of a regular arrangement of rockfill and notations](pam_schema_enrochement_regulier.png)