manual: fix string escapes in example (#1091)

Author: lsf37

docs/md/example.md

@@ -11,14 +11,15 @@ section presents a part of the specification for the Java language.
 
 The example does not describe the whole lexical structure of Java programs,
 but only a small and simplified part of it:
+
 - some keywords,
 - some operators,
-- comments 
+- comments
 - and only two kinds of literals.
 
-It also shows how to interface with the LALR parser generator CUP [@CUP] 
+It also shows how to interface with the LALR parser generator CUP [@CUP]
 and therefore uses a class `sym` (generated by CUP), where integer constants
-for the terminal tokens of the CUP grammar are declared. 
+for the terminal tokens of the CUP grammar are declared.
 
 You can find this example in `examples/cup-java-minijava`.
 
@@ -29,7 +30,7 @@ interface with the JFlex scanner). Both specifications adhere to the Java
 Language Specification [@LangSpec].
 
 In `examples/standalone`, you can find a small standalone scanner that
-doesn’t need other dependencies or tools like CUP to give you working code. 
+doesn’t need other dependencies or tools like CUP to give you working code.
 
 
 ```
@@ -85,9 +86,9 @@ doesn’t need other dependencies or tools like CUP to give you working code.
     <YYINITIAL> "break"              { return symbol(sym.BREAK); }
 
     <YYINITIAL> {
-      /* identifiers */ 
+      /* identifiers */
       {Identifier}                   { return symbol(sym.IDENTIFIER); }
-     
+
       /* literals */
       {DecIntegerLiteral}            { return symbol(sym.INTEGER_LITERAL); }
       \"                             { string.setLength(0); yybegin(STRING); }
@@ -99,22 +100,22 @@ doesn’t need other dependencies or tools like CUP to give you working code.
 
       /* comments */
       {Comment}                      { /* ignore */ }
-     
+
       /* whitespace */
       {WhiteSpace}                   { /* ignore */ }
     }
 
     <STRING> {
-      \"                             { yybegin(YYINITIAL); 
-                                       return symbol(sym.STRING_LITERAL, 
+      \"                             { yybegin(YYINITIAL);
+                                       return symbol(sym.STRING_LITERAL,
                                        string.toString()); }
       [^\n\r\"\\]+                   { string.append( yytext() ); }
       \\t                            { string.append('\t'); }
       \\n                            { string.append('\n'); }
 
       \\r                            { string.append('\r'); }
       \\\"                           { string.append('\"'); }
-      \\                             { string.append('\\'); }
+      \\\\                           { string.append('\\'); }
     }
 
     /* error fallback */