reword the algorithm to make it clearer

src/13_semiconductors.md

@@ -168,10 +168,11 @@ $$ g(E_h) = (2m_h)^{3/2}\sqrt{E_h}/2\pi^2\hbar^3$$
 
 **The key algorithm of describing the state of a semiconductor:**
 
-1. Write down the density of states, assuming a certain position of the Fermi level
-2. Calculate the total amount of electrons and holes, equate the difference to the total amount of electrons $-$ holes available.
-3. Use physics intuition to simplify the equations (this is important!)
-4. Find $E_F$ and concentrations of electrons and holes
+1. Compute the density of states of all types of particles.
+2. Calculate the total amount of electrons and holes, assuming a certain value of $E_F$
+3. Write down the charge balance condition: the difference between electrons and holes should equal to the total charge of the semiconductor.
+4. Apply approximations to simplify the equations (this is important!).
+5. Find $E_F$ and concentrations of electrons and holes
 
 Applying the algorithm: