Remove text on Julia <v.16 limitations from docs

Makes docs more readable and use of Julia v1.0 is very rare.

Author: oschulz

docs/src/index.md

@@ -6,6 +6,6 @@ InverseFunctions
 
 This package defines the function [`inverse`](@ref). `inverse(f)` returns the inverse function of a function `f`, so that `inverse(f)(f(x)) ≈ x`.
 
-`inverse` supports mapped/broadcasted functions (via `Base.Broadcast.BroadcastFunction` or `Base.Fix1`) and (on Julia >=v1.6) function composition.
+`inverse` supports mapped/broadcasted functions (via `Base.Broadcast.BroadcastFunction` or `Base.Fix1`) and function composition.
 
 Implementations of `inverse(f)` for `identity`, `inv`, `adjoint` and `transpose` as well as for `exp`, `log`, `exp2`, `log2`, `exp10`, `log10`, `expm1`, `log1p` and `sqrt` are included.