Remove out-of-date notes in documentation (#302)

Author: giordano

docs/src/index.md

@@ -1,43 +1,15 @@
 # Special Functions
 
-This package provides a comprehensive collection of special functions based on the
+[`SpecialFunctions.jl`](https://github.com/JuliaMath/SpecialFunctions.jl/edit/master/docs/src/index.md) provides a comprehensive collection of special functions based on the
 [OpenSpecFun](https://github.com/JuliaLang/openspecfun) and [OpenLibm](https://github.com/JuliaLang/openlibm)
 libraries.
 
 ## Installation
 
-The package is available for Julia versions 0.5 and up. To install it, run
+The latest version of the package is available for Julia versions 1.3 and up. To install it, run
 
 ```julia
 Pkg.add("SpecialFunctions")
 ```
 
-from the Julia REPL.
-
-## Note
-
-Prior to Julia 0.6, most of these functions were available in Julia's `Base` module.
-Because of this, the symbols from this package are not exported on Julia 0.5
-to avoid name conflicts.
-In this case, the symbols will need to be explicitly imported or called
-with the prefix `SpecialFunctions`.
-This is not necessary for Julia versions 0.6 and later.
-
-On Julia 0.7, [openspecfun](https://github.com/JuliaLang/openspecfun) is not built as
-part of Julia.
-Thus for Julia versions 0.7 and later, installing this package downloads openspecfun.
-Binaries of openspecfun are available for macOS, Windows, and Linux (glibc >= 2.6).
-Other systems will need to build the library from source.
-You can force a build from source by setting an environment variable called
-`JULIA_SPECIALFUNCTIONS_BUILD_SOURCE` equal to `true` before running `Pkg.build`.
-This ensures that the library is built locally from source, even if binaries are
-available.
-Doing this requires a C compiler (Clang on macOS and FreeBSD, GCC elsewhere) and
-gfortran.
-If you always want to build this library from source, consider adding
-
-```julia
-ENV["JULIA_SPECIALFUNCTIONS_BUILD_SOURCE"] = "true"
-```
-
-to your `.juliarc.jl` file.
+from the Julia REPL.  Earlier versions of `SpecialFunctions.jl` are available also for Julia v0.5-1.2.