Adding the missing roc:: namespace (#570)

* Adding the missing roc:: namespace, effectively changing the value of RCCL_LIBRARY from rccl to roc::rccl.
The important difference is that rccl is treated as a symbolic "-lrccl" by linker (and fail the linking
due to a missing library search path), while roc::rccl is a target name, which can resolve into an absolute
library path.

Co-authored-by: Paul Fultz II <pfultz2@yahoo.com>

* Adding a changelog entry

* minor updates to wording

* missing period

Co-authored-by: Paul Fultz II <pfultz2@yahoo.com>
Co-authored-by: Saad Rahim <44449863+saadrahim@users.noreply.github.com>

CHANGELOG.md

@@ -5,6 +5,8 @@ Full documentation for RCCL is available at [https://rccl.readthedocs.io](https:
 ## (Unreleased) RCCL-2.12.10
 ### Added
 - Compatibility with NCCL 2.12.10
+- Changing CMake exported target name from rccl to roc::rccl. This aligns RCCL to other ROCm
+  components. Users may need to update their build systems. 
 - Packages for test and benchmark executables on all supported OSes using CPack.
 - Adding custom signal handler - opt-in with RCCL_ENABLE_SIGNALHANDLER=1
   - Additional details provided if Binary File Descriptor library (BFD) is pre-installed

CMakeLists.txt

@@ -348,7 +348,7 @@ rocm_install(FILES ${PROJECT_BINARY_DIR}/include/rccl/rccl.h
 rocm_export_targets(NAMESPACE
                     roc::
                     TARGETS
-                    rccl
+                    roc::rccl
                     DEPENDS
                     hip)
 if(BUILD_FILE_REORG_BACKWARD_COMPATIBILITY)