DOC: CONTRIBUTING.md link to ITK Software Guide Development Guidelines
DOC: CONTRIBUTING.md link to ITK Software Guide Development Guidelines

Kitware/ITK,BRAINSia/ITK,Kitware/ITK,BRAINSia/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,LucasGandel/ITK,hjmjohnson/ITK,BRAINSia/ITK,Kitware/ITK,richardbeare/ITK,richardbeare/ITK,richardbeare/ITK,BRAINSia/ITK,vfonov/ITK,vfonov/ITK,hjmjohnson/ITK,LucasGandel/ITK,malaterre/ITK,vfonov/ITK,InsightSoftwareConsortium/ITK,vfonov/ITK,vfonov/ITK,vfonov/ITK,richardbeare/ITK,BRAINSia/ITK,richardbeare/ITK,LucasGandel/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,malaterre/ITK,LucasGandel/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,richardbeare/ITK,vfonov/ITK,thewtex/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,vfonov/ITK,LucasGandel/ITK,hjmjohnson/ITK,malaterre/ITK,BRAINSia/ITK,InsightSoftwareConsortium/ITK,Kitware/ITK,thewtex/ITK,LucasGandel/ITK,vfonov/ITK,Kitware/ITK,BRAINSia/ITK,LucasGandel/ITK,richardbeare/ITK,thewtex/ITK,hjmjohnson/ITK,malaterre/ITK,thewtex/ITK,thewtex/ITK,hjmjohnson/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,thewtex/ITK,LucasGandel/ITK,hjmjohnson/ITK,Kitware/ITK,malaterre/ITK