📚 Update EulerAngleAxis documentation

Author: ronisbr

docs/src/man/euler_angle_axis.md

@@ -1,19 +1,51 @@
 Euler Angle and Axis
 ====================
 
+```@meta
+CurrentModule = ReferenceFrameRotations
+DocTestSetup = quote
+    using ReferenceFrameRotations
+end
+```
+
 The Euler angle and axis representation is defined by the following immutable
 structure:
 
 ```julia
 struct EulerAngleAxis{T}
     a::T
-    v::Vector{T}
+    v::SVector{3,T}
 end
 ```
 
 in which `a` is the Euler Angle and `v` is a unitary vector aligned with the
 Euler axis.
 
+The constructor for this structure is:
+
+```julia
+function EulerAngleAxis(a::T1, v::AbstractVector{T2}) where {T1,T2}
+```
+
+in which a `EulerAngleAxis` with angle `a [rad]` and vector `v` will be created.
+Notice that the type of the returned structure will be selected according to the
+input types `T1` and `T2`. Furthermore, the vector `v` **will not** be
+normalized.
+
+```jldoctest
+julia> EulerAngleAxis(1,[1,1,1])
+EulerAngleAxis{Int64}(1, [1, 1, 1])
+
+julia> EulerAngleAxis(1.f0,[1,1,1])
+EulerAngleAxis{Float32}(1.0f0, Float32[1.0, 1.0, 1.0])
+
+julia> EulerAngleAxis(1,[1,1,1.f0])
+EulerAngleAxis{Float32}(1.0f0, Float32[1.0, 1.0, 1.0])
+
+julia> EulerAngleAxis(1.0,[1,1,1])
+EulerAngleAxis{Float64}(1.0, [1.0, 1.0, 1.0])
+```
+
 !!! note
 
     The support of this representation is still incomplete. Only the conversion