doc: remove extraneous install statement

Author: tdb3

Diff for: doc/build-openbsd.md

@@ -90,7 +90,7 @@ There is an included test suite that is useful for testing code changes when dev
 To run the test suite (recommended), you will need to have Python 3 installed:
 
 ```bash
-pkg_add install python  # Select the newest version of the package.
+pkg_add python  # Select the newest version of the package.
 ```
 
 ## Building Bitcoin Core