fixups to latex formatting (passing check-source.sh)

Author: notadragon

source/intro.tex

@@ -952,9 +952,9 @@
 of the abstract machine with the
 same program and the same input.
 \indextext{behavior!undefined}%
-If the selected execution contains an undefined operation, 
+If the selected execution contains an undefined operation,
 the implementation executing that program with that input
-may produce arbitrary additional observable behavior aferwards. 
+may produce arbitrary additional observable behavior aferwards.
 If the execution contains an operation specified as having erroneous behavior,
 the implementation is permitted to issue a diagnostic and
 is permitted to terminate the execution