Adding docs for parametrizing integration domain

[gomezzz]

Description

Summary of changes

Better docs for parametrized integration

Resolved Issues

• fixes Example/documentation for parametric domain of integration? #186

How Has This Been Tested?

Only doc change

Related Pull Requests

• builds on Moving tests outside module #218

[github-actions]

Coverage Report

File	Stmts	Miss	Cover	Missing
torchquad/integration
base_integrator.py	49	7	86%	28, 64–67, 71, 106, 110, 115
boole.py	30	3	90%	53, 72–75
gaussian.py	52	3	94%	77, 101, 119
grid_integrator.py	101	3	97%	41, 151, 255
integration_grid.py	49	6	88%	47–48, 55–56, 115, 118
monte_carlo.py	93	3	97%	80, 99, 225
rng.py	62	24	61%	70–73, 90–118, 138
simpson.py	29	3	90%	51, 70–73
utils.py	118	10	92%	101, 136, 166, 170, 177, 189, 191, 197, 269, 276
vegas.py	161	5	97%	96, 100–101, 187, 334
vegas_map.py	98	6	94%	244–254
torchquad/plots
plot_convergence.py	13	10	23%	15–25
plot_runtime.py	8	6	25%	14–19
torchquad/utils
deployment_test.py	41	35	15%	18–62
enable_cuda.py	12	6	50%	16–21
set_precision.py	28	3	89%	34–37, 70
set_up_backend.py	19	1	95%	12
TOTAL	1069	134	87%

Tests	Skipped	Failures	Errors	Time
53	0 💤	0 ❌	0 🔥	1m 54s ⏱️