Update CONTRIBUTING.md (#652)

CONTRIBUTING.md

@@ -9,18 +9,13 @@ to contribute to the contents of this repository, hereafter referred to as
 General
 -------
 All contributors implicitly agree to license their contribution under the same
-terms as the rest of the software, and accept that those terms may change in the
-future.  See the `LICENCE.txt` file for details.
+terms as the rest of the software.  See the `LICENSE` file for details.
 
 All contributions to the software, in the form of changes, removals or
 additions to source code and other files under source control, shall be made
 via pull requests.  A pull request must always be reviewed and merged by someone
 other than its author.
 
-Before a pull request can be approved and merged into the code base, the author 
-must sign the "OSP Contributor License Agreement". This agreement is pending, but 
-will be included in this repository with guidelines once concluded.
-
 Programming language and style
 ------------------------------
 The primary programming language is C++, specifically C++17.