Explanation of the use of the symbols µ and ° added

README.md

@@ -82,7 +82,7 @@ Now that the library es linked, you can use it inside your code by including the
 | --- | -----
 | θ | String literal of angle and used both in vector_unit_2d and vector_unit_3d.
 | Φ | Angle phi, used in vector_unit_3d.
-| ° | Degree, used in vector_unit_nd.
+| ° | Degree, used in vector_unit_nd and angle class.
 | Ω | String literal of resistance.
 | Å | String literal of angstrom.
 | µ | Prefix micro, used as part of the string literals with micro.

docs/dox/meca_number/angle.dox

@@ -1,5 +1,5 @@
 /** \class scifir::angle
-* \brief Class that allows to work with angles. Each angle sizes 4 bytes.
+* \brief Class that allows to work with angles. Each angle sizes 4 bytes. **Initialization string** example: "20°".
 
 * angle is a class that allows to work with angles, more in degrees than in radians. The value of the angle is always stored inside the class in degrees, and it can be get in radians with the to_radian() function.
 

docs/dox/units/prefix.dox

@@ -1,5 +1,5 @@
 /** \class scifir::prefix
-* \brief Class that represents prefixes of the SI system of units. Each prefix sizes 1 byte.
+* \brief Class that represents prefixes of the SI system of units. Each prefix sizes 1 byte. The prefix micro is added to a dimension with the symbol **µ**.
 
 * \enum scifir::prefix::type
 * \brief Represents a prefix of the SI system of units. All the prefixes of the SI system of units are supported.