[docs] Document lit's --timeout=N flag

Author: jroelofs

llvm/docs/CommandGuide/lit.rst

@@ -165,10 +165,8 @@ SELECTION OPTIONS
 .. option:: --max-time=N
 
  Spend at most ``N`` seconds (approximately) running tests and then terminate.
-
-.. option:: --shuffle
-
- Run the tests in a random order.
+ Note that this is not an alias for :option:``--timeout=N``; the two are
+ different kinds of maximums.
 
 .. option:: --num-shards=M
 
@@ -187,6 +185,16 @@ SELECTION OPTIONS
  must be in the range ``1..M``. The environment variable
  ``LIT_RUN_SHARD`` can also be used in place of this option.
 
+.. option:: --shuffle
+
+ Run the tests in a random order.
+
+.. option:: --timeout=N
+
+ Spend at most ``N`` seconds (approximately) running each individual test.
+ ``0`` means no time limit, and ``0`` is the default. Note that this is not an
+ alias for :option:``--max-time=N``; the two are different kinds of maximums.
+
 .. option:: --filter=REGEXP
 
   Run only those tests whose name matches the regular expression specified in