document --enable-max-accsets

* README, doc/org/hoa.org: Here.

README

@@ -115,6 +115,14 @@ flags specific to Spot:
     do not have a working Python 3.2+ installation or if you are
     attempting some cross-compilation.
 
+  --enable-max-accsets=N
+    Compile Spot so that it supports up to N acceptance sets.  The
+    default is 32, so that the membership of each transition to
+    any of the 32 acceptance sets can be represented by an
+    "unsigned int" (interpreted as a bit-vector).  Using a larger
+    N (it still has to be a multiple of 32) will consume more
+    unsigned ints per transitions, costing both time and space.
+
   --enable-doxygen
     Generate the Doxygen documentation for the code as part of the
     build.  This requires Doxygen to be installed.  Even if

doc/org/hoa.org

@@ -58,14 +58,15 @@ the HOA format, the output may not be exactly the same as the input.
 - Automata using explicit alphabet (introduced in version 1.1 of the
   format via =Alphabet:=) are not supported.
 
-- The maximum number of acceptance sets used is (currently) limited
+- The maximum number of acceptance sets used is limited to 32.
-  to 32.
 
-  This limit is not very hard to increase in the source code,
+  In the past, this limitation has forced us to improve some of our
-  however we want to keep it until it becomes an actual problem.  So
+  algorithms to be less wasteful and not introduce useless acceptance
-  please report to us if you suffer from it.  In the past, this
+  sets.
-  limitation has forced us to improve some of our algorithms to be
+
-  less wasteful and not introduce useless acceptance sets.
+  This hard-coded limit can be augmented at configure time
+  using option `--enable-max-accsets=N`, but doing so will consume
+  more memory and time.
 
 - Multiple (or missing) initial states are emulated.