Tweaks and docs

bpeg.1

@@ -145,6 +145,10 @@ be a string, and it may contain references to captured values: \fB@0\fR
 Will match only if \fI<pat1>\fR and \fI<pat2>\fR both match and have the exact
 same length. Pronounced \fI<pat1>\fB-assuming-it-equals-\fI<pat2>\fR
 
+.B |
+This pattern matches the indentation at the beginning of a line that has the
+same indentation as the line before (or zero indentation on the first line).
+
 .B (/)
 The empty string (a pattern that always matches).
 

grammars/builtins.bpeg

@@ -8,8 +8,8 @@ only-matches = +{...@pattern=>'@1\n'};
 matching-line = +(..@pattern) ..$;
 
 # Helper definitions (commonly used)
-indent = \n |+(\t/' ');
-dedent = >(\n !|);
+indent = \n|+(\t/' ');
+dedent = $ !(\n|);
 indented-block = |` ..$ *(\n|..$);
 crlf = \r\n;
 cr = \r; r = \r;