doc: sample: add/update sample source files

doc/sample/syntax.bshell

@@ -31,12 +31,12 @@ $a$b
 # VAR(a)
 # VAR(b)
 
-# When the parser encounters SYMBOL(%) it should switch the lexer to COMMAND
+# When the parser encounters SYMBOL(&) it should switch the lexer to COMMAND
 # mode, which will allow the following word construction to be used.
 # this executes the command whose name is equal to concatenating the values
 # of $a and $b (in this case, '24')
-% $a$b
-# SYMBOL(%)
+& $a$b
+# SYMBOL(&)
 # WORD_START
 # VAR(a)
 # VAR(b)
@@ -51,7 +51,7 @@ a+2b
 # the first char encountered is a symbol, which is read as a word in COMMAND
 # mode
 -no$a
-# WORD(-no)
+# WORD(-no$a)
 
 # returns the result of applying the NOT operator to the value of $a.
 # the first char encountered is a symbol, which is read as a word in COMMAND
@@ -62,16 +62,19 @@ a+2b
 # OP(not)
 # VAR(a)
 
-# executes the command with the name '-not$a' ($a is NOT substituted)
+# executes the command with the name '-not$a' ($a is substituted)
 # because of the preceding hyphen, variable substitution is not performed.
-% -not$a
-# SYMBOL(%)
-# WORD(-not$a)
+& -not$a
+# SYMBOL(&)
+# WORD_START
+# WORD(-not)
+# VAR(a)
+# WORD_END
 
-# executes the command with the name '-not2' ($a IS substituted)
+# executes the command with the name "-not$a" ($a IS substituted)
 # variable substitution IS performed in dquote strings regardless of the hyphen.
-% "-not$a"
-# SYMBOL(%)
+& "-not$a"
+# SYMBOL(&)
 # STR_START
 # STRING(-not)
 # VAR(a)