Update BUILD.md: revise troubleshooting section

BUILD.md

@@ -108,18 +108,13 @@ To test the LP support use:
 ./fast-downward.py misc/tests/benchmarks/miconic/s1-0.pddl --search "astar(operatorcounting([lmcut_constraints()]))"
 ```
 
-# Troubleshooting
-
-[[keep a troubleshooting section; perhaps include rm -rf build here; make this a generic troubleshooting section, not an LP-specific one]]
-
-If you get warnings about unresolved references with CPLEX, visit their [[http://www-01.ibm.com/support/docview.wss?uid=swg21399926|help pages]].
-
-If you compiled Fast Downward on Windows (especially on !GitHub Actions) and cannot execute the binary in a new command line, then it might be unable to find a dynamically linked library. Use {{{dumpbin /dependents PATH\TO\DOWNWARD\BINARY}}} to list all required libraries and ensure that they can be found in your {{{PATH}}} variable.
-=> is this still current?
-
-IBM offers a [free academic license](http://ibm.com/academic) that includes access to CPLEX.
-Once you are registered, you find the software under Technology -> Data Science. Choose the right version and switch to HTTP download unless you have the IBM download manager installed. If you have problems using their website with Firefox, try Chrome instead. Execute the downloaded binary and follow the guided installation.
-
-
-Building VAL on macOS: If your compiler doesn't find flex or bison, your include directories might be in a non-standard location. In this case you probably have to specify where to look for includes and libraries in VAL's Makefile (probably `/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr`).
+## Troubleshooting
+
+* If you changed the build environment, delete the `builds` directory and rebuild.
+* **Windows:** If you cannot execute the Fast Downward binary in a new command line, then it might be unable to find a dynamically linked library.
+  Use `dumpbin /dependents PATH\TO\DOWNWARD\BINARY` to list all required libraries and ensure that they can be found in your `PATH` variable.
+* **CPLEX:** After logging in at the IBM website, you find the Ilog studio software under Technology -> Data Science. Choose the right version and switch to HTTP download unless you have the IBM download manager installed. If you have problems using their website with Firefox, try Chrome instead. Execute the downloaded binary and follow the guided installation.
+* **CPLEX:** If you get warnings about unresolved references with CPLEX, visit their [help pages](http://www-01.ibm.com/support/docview.wss?uid=swg21399926).
+* **MacOS:** If your compiler doesn't find flex or bison when building VAL, your include directories might be in a non-standard location. In this case you probably have to specify where to look for includes and libraries in VAL's   
+  Makefile (probably `/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr`).