Fix markdown code for pcb calculator

Avoid '%' in translated strings and simplify the language used in
eserie_help

pcb_calculator/eserie_help.md

@@ -1,31 +1,25 @@
 E-series defined in IEC 60063 are a widely accepted system of preferred
 numbers for electronic components.  Available values are approximately
-equally spaced in a logarithmic scale.  Although E-series are used for
-Zener diodes, inductors and other components, this calculator is mainly
-intended for resistors.
+equally spaced in a logarithmic scale.
 
 	E12: 1,0 1,2 1,5 1,8 2,2 2,7 3,3 3,9 4,7 5,6 6,8 8,2
 	E6:  1,0  -  1,5  -  2,2  -  3,3  -  4,7  -  6,8  -
 	E3:  1,0  -   -   -  2,2  -   -   -  4,7  -   -   -
 	E1:  1,0  -   -   -   -   -   -   -   -   -   -   -
-If your design requires any resistor value which is not readily available,
-this calculator will find a combination of standard E-series components to
-create it.  You can enter the required resistance from 0,0025 to 4000 kOhm. 
-Solutions using 3 or 4 resistors are given if a better match can be found. 
-The 4R checkbox option will take longer to process is considered for the E12
-series only.  Optionally it is possible to exclude up to two additional
-values from the solution for the reason of being not available.  If a
-E-series value is entered to the required input field, it is always excluded
-from any solution as it is assumed that this value is unavailable.
+
+This calculator finds combinations of standard E-series components to
+create arbitrary values.  You can enter the required resistance from 0,0025 to 4000 kOhm. 
+Solutions using up to 3 components are given.  
+
+If a closer solutions is needed, the 4R checkbox option will give solutions 
+using 4 components for the E12 series only.  This option
+may take longer to compute.  
+
+It is also possible to specify up to two values to exclude from the solution if these
+component values are not available
 
 Solutions are given in the following formats:
 
 	R1 + R2 +...+ Rn	resistors in series
 	R1 | R2 |...| Rn	resistors in parallel
 	R1 + (R2|R3)...		any combination of the above
-__Example:__ Voltage dividers, commonly used for 1:10 range selection
-require resistor ratio values 1:9.  Unfortunately the "9" is a value, what
-is not even in the E192 series available.  Deviation of 1% and more is yet
-unacceptable for 8 bit accuracy.  For a required resistor value of 9 kOhm,
-the calculator suggests the E6 values 2k2 + 6k8 in series as a possible
-exact solution.