DOC: Advise users to delete the PR template in message.
DOC: Advise users to delete the PR template in message.

Improve the PR template message to highlight the fact that it is a set of
guidelines that should be removed for the final PR message.

Kitware/ITK,Kitware/ITK,fbudin69500/ITK,vfonov/ITK,spinicist/ITK,richardbeare/ITK,spinicist/ITK,thewtex/ITK,blowekamp/ITK,malaterre/ITK,blowekamp/ITK,spinicist/ITK,Kitware/ITK,LucasGandel/ITK,malaterre/ITK,LucasGandel/ITK,malaterre/ITK,LucasGandel/ITK,BRAINSia/ITK,vfonov/ITK,fbudin69500/ITK,BRAINSia/ITK,LucasGandel/ITK,Kitware/ITK,malaterre/ITK,hjmjohnson/ITK,BRAINSia/ITK,thewtex/ITK,vfonov/ITK,vfonov/ITK,fbudin69500/ITK,InsightSoftwareConsortium/ITK,blowekamp/ITK,fbudin69500/ITK,LucasGandel/ITK,Kitware/ITK,InsightSoftwareConsortium/ITK,BRAINSia/ITK,vfonov/ITK,spinicist/ITK,LucasGandel/ITK,spinicist/ITK,fbudin69500/ITK,blowekamp/ITK,richardbeare/ITK,InsightSoftwareConsortium/ITK,InsightSoftwareConsortium/ITK,thewtex/ITK,hjmjohnson/ITK,richardbeare/ITK,vfonov/ITK,hjmjohnson/ITK,malaterre/ITK,malaterre/ITK,fbudin69500/ITK,Kitware/ITK,blowekamp/ITK,LucasGandel/ITK,richardbeare/ITK,blowekamp/ITK,richardbeare/ITK,LucasGandel/ITK,thewtex/ITK,blowekamp/ITK,vfonov/ITK,thewtex/ITK,blowekamp/ITK,spinicist/ITK,BRAINSia/ITK,thewtex/ITK,malaterre/ITK,Kitware/ITK,fbudin69500/ITK,hjmjohnson/ITK,spinicist/ITK,fbudin69500/ITK,vfonov/ITK,malaterre/ITK,BRAINSia/ITK,richardbeare/ITK,InsightSoftwareConsortium/ITK,hjmjohnson/ITK,richardbeare/ITK,InsightSoftwareConsortium/ITK,malaterre/ITK,InsightSoftwareConsortium/ITK,spinicist/ITK,thewtex/ITK,hjmjohnson/ITK,hjmjohnson/ITK,vfonov/ITK,BRAINSia/ITK,spinicist/ITK