[Doc] small fixes

Documentation/ProjectFile/prj/curves/i_curves.md

 Contains curve definitions.
 
 Curves are scalar valued functions of a scalar argument.
-They can be used, e.g., to define time-dependent quantities.
+They can be used, e.g., to define time-dependent quantities, or simple
+relationships of scalar quantities as viscosity from temperature.

Documentation/ProjectFile/prj/process_variables/process_variable/t_initial_condition.md

 Initial condition for the process variable.
 
 This setting references a \ref ogs_file_param__parameter "parameter" by name.
+
+The initial values of the process variable are read from the given initial
+condition, i.e., in the very first assembly the values for this process varaible
+are those given in the IC.

Documentation/ProjectFile/process/secondary_variables/secondary_variable/a_type.md

 The type of the secondary variable.
 
 Can be <tt>static</tt> for secondary variables that don't need any further
-information from the project file in order to be computer;
+information from the project file in order to be computed;
 or <tt>dynamic</tt> if the functions providing some of the input data for
 computing the secondary variable are set up at runtime.