[NFC] Add GitHub actions badges to README file (#1496)

Two badges showing status of post-commit checks on Linux and Doxygen
documentation generator.

Signed-off-by: Alexey Bader <[email protected]>

Author: bader

README.md

@@ -7,6 +7,9 @@ Home for Intel LLVM-based projects:
  - oneAPI Data Parallel C++ compiler - see **sycl** branch. More information on
    oneAPI and DPC++ is available at
 ([https://www.oneapi.com/](https://www.oneapi.com/))
+   - [![Linux Post Commit Checks](https://github.com/intel/llvm/workflows/Linux%20Post%20Commit%20Checks/badge.svg)](https://github.com/intel/llvm/actions?query=workflow%3A%22Linux+Post+Commit+Checks%22) [![Generate Doxygen documentation](https://github.com/intel/llvm/workflows/Generate%20Doxygen%20documentation/badge.svg)](https://github.com/intel/llvm/actions?query=workflow%3A%22Generate+Doxygen+documentation%22)
+
+
 
 ## License
 See [LICENSE.txt](sycl/LICENSE.TXT) for details.