Move license text to docs/src/index.md

Author: abhro

docs/src/basicUsage.md

@@ -403,8 +403,3 @@ replace_head(tan(sin(tan(x))), tan, cos)
 ## `SymEngine.jl` and symengine
 
 This package only wraps those parts of symengine that are exposed through its [C wrapper](https://github.com/symengine/symengine/blob/master/symengine/cwrapper.cpp). The underlying C++ library has more functionality.
-
-
-## License
-
-`SymEngine.jl` is licensed under the MIT open source license.

docs/src/index.md

@@ -13,3 +13,7 @@ The package and dependencies can be obtained with standard `Pkg` calls.
 ```julia
 julia> Pkg.add("SymEngine")
 ```
+
+## License
+
+`SymEngine.jl` is licensed under the MIT open source license.