Fix typos in UnitfulConversion() documentation (#4820)

Fix typos in UnitfulConversion documentation

Author: ckumarad

src/dim-converts/unitful-integration.jl

@@ -140,7 +140,7 @@ scatter(1:4, [1u"ns", 2u"ns", 3u"ns", 4u"ns"])
 Fix unit to always use Meter & display unit in the xlabel:
 ```julia
 uc = Makie.UnitfulConversion(u"m"; units_in_label=false)
-scatter(1:4, [0.01u"km", 0.02u"km", 0.03u"km", 0.04u"km"]; axis=(dim2_conversion=uc, xlabel="x (km)"))
+scatter(1:4, [0.01u"km", 0.02u"km", 0.03u"km", 0.04u"km"]; axis=(dim2_conversion=uc, ylabel="y (m)"))
 ```
 """
 struct UnitfulConversion <: AbstractDimConversion