Need to document that TUI entries that are required as strings need to be quoted twice

[sujal-tipnis]

To reproduce:
Run the following code:

import ansys.fluent.core as pyfluent
# from ansys.fluent.core import examples
session = pyfluent.launch_fluent(precision="double", processor_count=2, version="2d")
session.tui.solver.file.read_case("inkjet.msh")
session.tui.solver.file.read_case("inkjet.msh")
root = session.get_settings_root()
session.tui.solver.mesh.check()
session.tui.solver.define.models.viscous.laminar("yes")
session.tui.solver.mesh.scale(1e-6,1e-6)
session.tui.solver.mesh.check()
session.tui.solver.define.units("length","mm")
session.tui.solver.define.units("surface-tension","dyn/cm")
session.tui.solver.define.models.unsteady_1st_order("yes")
session.tui.solver.define.models.axisymmetric("yes")
session.tui.solver.define.models.multiphase.model("vof")
session.tui.solver.define.models.multiphase.volume_fraction_parameters("explicit",0.25,",")
session.tui .solver.define.materials.copy("fluid","water-liquid")
session.tui.solver.define.materials.change_create("water-liquid",",", ",", ",", ",", ",", ",", ",", ",")
session.tui.solver.define.phases.set_domain_properties.phase_domains("phase-1","material","no")
session.tui.solver.define.phases.set_domain_properties.phase_domains("phase-2","material","yes","water-liquid")
session.tui.solver.define.phases.set_domain_properties.interaction_domain.forces.surface_tension.sfc_tension_coeff("yes","constant","74")
session.tui.solver.define.operating_conditions.reference_pressure_location("0.1","0.03")
session.tui.solver.define.boundary_conditions.velocity_inlet('inlet','mixture','no','no','yes','yes','no',"IF(t<=10e-6[sec],3.58[m/s]*cos(PI*t/30e-6[s]),0[m/s])",'no','0')

Use the msh file from the following location
Open the Fluent UI for the mixture inlet and check the expression.
This expression is not specified.

[mkundu1]

Expression input in the TUI API is working:

>>> import ansys.fluent.core as pyfluent
>>> session = pyfluent.launch_fluent()
>>> session.solver.tui.file.read_case("elbow.cas.gz")
>>> session.solver.tui.define.boundary_conditions.velocity_inlet("inlet2", "no", "no", "yes", "yes", "no", '"IF(t<=10e-6[sec],3.58[m/s]*cos(PI*t/30e-6[s]),0[m/s])"', "no", 0, "no", 300, "no", "no", "no", 
"yes", 10, 0.04)

As expressions are input like string in the Fluent TUI, they should be quoted twice from PyFluent.