Update examples/README with correct starter templates link

[Enigo]

I've noticed that https://yew.rs/docs/getting-started/starter-templates doesn't exist anymore.
Assuming that it should now point to https://yew.rs/docs/getting-started/build-a-sample-app#using-a-starter-template

[github-actions]

Size Comparison

examples	master (KB)	pull request (KB)	diff (KB)	diff (%)
async_clock	107.873	107.873	0	0.000%
boids	170.760	170.767	+0.007	+0.004%
communication_child_to_parent	90.831	90.836	+0.005	+0.005%
communication_grandchild_with_grandparent	105.160	105.164	+0.004	+0.004%
communication_grandparent_to_grandchild	100.996	100.998	+0.002	+0.002%
communication_parent_to_child	87.927	87.932	+0.005	+0.006%
contexts	107.707	107.705	-0.002	-0.002%
counter	85.731	85.732	+0.001	+0.001%
counter_functional	86.043	86.044	+0.001	+0.001%
dyn_create_destroy_apps	88.512	88.513	+0.001	+0.001%
file_upload	100.191	100.193	+0.002	+0.002%
function_memory_game	164.879	164.874	-0.005	-0.003%
function_router	349.516	349.524	+0.009	+0.003%
function_todomvc	159.861	159.867	+0.006	+0.004%
futures	224.483	224.483	0	0.000%
game_of_life	106.489	106.490	+0.001	+0.001%
immutable	181.965	181.961	-0.004	-0.002%
inner_html	82.121	82.120	-0.001	-0.001%
js_callback	111.943	111.948	+0.005	+0.004%
keyed_list	196.188	196.198	+0.011	+0.005%
mount_point	85.359	85.359	0	0.000%
nested_list	113.392	113.396	+0.004	+0.003%
node_refs	93.370	93.377	+0.007	+0.007%
password_strength	1549.274	1549.274	0	0.000%
portals	96.562	96.562	+0.001	+0.001%
router	319.671	319.689	+0.019	+0.006%
simple_ssr	150.976	150.977	+0.001	+0.001%
ssr_router	394.699	394.702	+0.003	+0.001%
suspense	109.074	109.074	0	0.000%
timer	88.608	88.606	-0.002	-0.002%
todomvc	141.098	141.100	+0.002	+0.001%
two_apps	86.353	86.353	0	0.000%
web_worker_fib	151.895	151.909	+0.015	+0.010%
webgl	84.909	84.907	-0.002	-0.002%

✅ None of the examples has changed their size significantly.

[hamza1311]

Thanks for the contribution!