add upgrade help in docs

Author: fredrikekre

docs/src/index.md

@@ -14,3 +14,25 @@ Mutable versions [`MVector`](@ref), [`MMatrix`](@ref) and [`MArray`](@ref) are a
 as [`SizedArray`](@ref) for annotating standard `Array`s with static size information.
 Further, the abstract [`FieldVector`](@ref) can be used to make fast static vectors
 out of any uniform Julia "struct".
+
+## Migrating code from Julia v0.6 to Julia v0.7
+
+When upgrading code that is depending on **StaticArrays** the following notes may be helpful
+
+* `chol` has been renamed to `cholesky` and return a factorization object. To obtain the factor
+  use `C = cholesky(A).U`, just like for regular Julia arrays.
+
+* `lu` now return a factorization object instead of a tuple with `L`, `U`, and `p`.
+  They can be obtained by destructing via iteration (`L, U, p = lu(A)`) or by
+  using `getfield` (`F = lu(A); L, U, p = F.L, F.U, F.p`).
+
+* `qr` now return a factorization object instead of a tuple with `Q` and `R`.
+  They can be obtained by destructing via iteration (`Q, R = qr(A)`) or by
+  using `getfield` (`F = qr(A); Q, R = F.Q, F.R`)
+
+* `eig` has been renamed to `eigen`, which return a factorization object, rather than
+  a tuple with `(values, vectors)`. They can be obtained by destructing via iteration
+  (`values, vectors = eigen(A)`) or by using `getfield`
+  (`E = eigen(A); values, vectors = E.values, E.vectors`).
+
+* `unshift` and `shift` have been renamed to `pushfirst` and `popfirst`.