[trivial] Link to BUILD.md from README.md.

README.md

@@ -37,11 +37,15 @@ We test LP support with CPLEX 22.1.1 and SoPlex 6.0.3+. On Ubuntu we
 test both CPLEX and SoPlex. On Windows we currently only test CPLEX,
 and on macOS we do not test LP solvers (yet).
 
+## Build instructions
+
+See [BUILD.md](BUILD.md).
+
 
 ## Contributors
 
 The following list includes all people that actively contributed to
-Fast Downward, i.e. all people that appear in some commits in Fast
+Fast Downward, i.e., all people that appear in some commits in Fast
 Downward's history (see below for a history on how Fast Downward
 emerged) or people that influenced the development of such commits.
 Currently, this list is sorted by the last year the person has been