Added Changelog.md for 6.0.1

CHANGELOG.md

+# 6.0.1
+
+| Released 2015/03/02, [GitHub Release Link](https://github.com/ufz/ogs/releases/tag/6.0.1)
+
+The 6th version of OpenGeoSys (OGS) is under way. After single and coupled FORTRAN modules in ROCKFLOW 1+2, the C version 3 with dynamic data structures, the object-oriented C++ parallelized version 4, completed with data integration and visualization tools by version 5; ogs6 - as an open source project - is aimed at performing on supercomputing platforms and providing complete workflows for solving of coupled multi-field problems in real world applications. The major paradigms of ogs6 are being developer-friendly, performing, and user-friendly.
+
+## Important links:
+
+- Getting started tutorial: http://docs.opengeosys.org/docs/quickstart
+- Descriptions of selected benchmarks: http://docs.opengeosys.org/docs/benchmarks
+
+- Source code access: https://github.com/ufz/ogs
+- Developer guide: http://docs.opengeosys.org/docs/devguide
+
+## Release notes
+The first version ogs6 is dedicated for elliptic problems.
+
+### Features:
+ - Basic structures of processes
+ - Mathematical operations are based on Eigen3 library
+ - Linear solvers: DenseMatrix with Gauss elimination, and LIS (http://www.ssisc.org/lis/)
+ - XML based IO
+ - Standard finite element method (FEM)
+ - Available element types: lines, triangles, quads, hexahedra
+ - Dirichlet boundary conditions
+ - Linear elliptic solver (e.g. Groundwater flow) for scalar quantities in homogeneous media
+
+### Fixes
+- DenseMatrix Gauss algorithm pivoting
+
+## Test examples
+![](https://cloud.githubusercontent.com/assets/329493/6170573/ce9fd96c-b2d5-11e4-9936-a470e7be281f.png)
+
+ - Example 1: Unit square (access)
+ - Example 2: Unit cube (access): has 1000 hexahedra  elements with Dirichlet boundary conditions (u=1|x=0) and (u=-1|x=1)
+
+## Next steps
+
+### In development
+ - OGS#PETSc interface for parallel computing (02/2015*planned)
+ - Neuman boundary conditions (03/2015*planned)
+
+### Planned
+ - Parabolic solver