[SYCL][NFC] Simplifying contribution guidelines (#1644)

Removing sign-off requirement for PRs

Signed-off-by: Pavel V Chupin <pavel.v.chupin@intel.com>

Author: pvchupin

CONTRIBUTING.md

@@ -1,69 +1,15 @@
 # Contributing
 
 ## License
-Intel Project for LLVM\* technology is licensed under the terms of the
-Apache-2.0 with LLVM-exception license ([LICENSE.txt](llvm/LICENSE.TXT))
-to ensure our ability to contribute this project to the LLVM project
-under the same license.
 
-By contributing to this project, you agree to the Apache-2.0 with
-LLVM-exception license and copyright terms there in and release your
-contribution under these terms.
+Intel Project for LLVM\* technology is licensed under the terms of the Apache
+License v2.0 with LLVM Exceptions license ([LICENSE.txt](llvm/LICENSE.TXT)) to
+ensure our ability to contribute this project to the LLVM project under the
+same license.
 
-## Sign your work
-Please use the sign-off line at the end of your contribution. Your
-signature certifies that you wrote the contribution or otherwise have
-the right to pass it on as an open-source contribution, and that you
-agree to provide your contribution under the terms of the licenses
-noted above. The rules are pretty simple: if you can certify the
-below (from [developercertificate.org](http://developercertificate.org)):
-
-```
-Developer Certificate of Origin
-Version 1.1
-
-Copyright (C) 2004, 2006 The Linux Foundation and its contributors.
-660 York Street, Suite 102,
-San Francisco, CA 94110 USA
-
-Everyone is permitted to copy and distribute verbatim copies of this
-license document, but changing it is not allowed.
-
-Developer's Certificate of Origin 1.1
-
-By making a contribution to this project, I certify that:
-
-(a) The contribution was created in whole or in part by me and I
-    have the right to submit it under the open source license
-    indicated in the file; or
-
-(b) The contribution is based upon previous work that, to the best
-    of my knowledge, is covered under an appropriate open source
-    license and I have the right under that license to submit that
-    work with modifications, whether created in whole or in part
-    by me, under the same open source license (unless I am
-    permitted to submit under a different license), as indicated
-    in the file; or
-
-(c) The contribution was provided directly to me by some other
-    person who certified (a), (b) or (c) and I have not modified
-    it.
-
-(d) I understand and agree that this project and the contribution
-    are public and that a record of the contribution (including all
-    personal information I submit with it, including my sign-off) is
-    maintained indefinitely and may be redistributed consistent with
-    this project or the open source license(s) involved.
-```
-
-Then you just add a line to every git commit message:
-
-    Signed-off-by: Joe Smith <joe.smith@email.com>
-
-Use your real name (sorry, no pseudonyms or anonymous contributions.)
-
-If you set your `user.name` and `user.email` git configs, you can sign your
-commit automatically with `git commit -s`.
+By contributing to this project, you agree to the Apache License v2.0 with LLVM
+Exceptions and copyright terms there in and release your contribution under
+these terms.
 
 ## Contribution process