[petsc-announce] New PETSc website, documentation and 3.15.1 patch release

Dear PETSc users, We are migrating PETSc website and docs to a new location. https://petsc.org/release/ Let us know via petsc-users or petsc-maint if you encounter any issues. For now, the old website https://www.mcs.anl.gov/petsc/ will be accessible - but the content is frozen. The patch release petsc-3.15.1 is also available for download. https://petsc.org/release/download/ Satish