Fix line embedding

Signed-off-by: jolheiser <john.olheiser@gmail.com>

README.md

@@ -4,14 +4,25 @@ Embed "things" in your markdown files.
 
 Given the same input, `emdbed` should give idempotent results.
 
+To create an `emdbed` section, use a header and footer as follows
+```text
+<!-- emdbed: <file> [~<language>] [L<start-line>|/<start-regex>/] [L<end-line>|/<end-regex>/]
+<!-- /emdbed --> 
+```
+**NOTE:** The above snippet has an extra space at the end in order to keep it from recognizing the footer when generating this README.
+
+The regex is [Go flavored](https://golang.org/s/re2syntax), which you can test on [regex101](https://regex101.com/).
+
 ## Examples
 
-The following are generated using [readme.go](readme.go) and `go generate ./...`.
+The following are generated using [readme.go](readme.go) and `go generate ./...`.  
+Check the raw markdown for the header selectors used.
 
 An entire file:
 
 <!-- emdbed: emdbed_example_test.go -->
 ```go
+// Package emdbed is for embedding "things" in your markdown
 package emdbed
 
 import (
@@ -36,6 +47,7 @@ func Example() {
 	//func main() {
 	//	fmt.Println("Hello, world!")
 	//}
+	//
 	// ```
 	//<!-- /emdbed -->
 }
@@ -45,15 +57,15 @@ func Example() {
 
 Just the package:
 
-<!-- emdbed: emdbed_example_test.go L1 L1 -->
+<!-- emdbed: emdbed_example_test.go L2 L2 -->
 ```go
 package emdbed
 ```
 <!-- /emdbed -->
 
-First line until the end of imports:
+Package line until the end of imports:
 
-<!-- emdbed: emdbed_example_test.go L1 /\)/ -->
+<!-- emdbed: emdbed_example_test.go L2 /\)/ -->
 ```go
 package emdbed
 
@@ -85,6 +97,7 @@ func Example() {
 	//func main() {
 	//	fmt.Println("Hello, world!")
 	//}
+	//
 	// ```
 	//<!-- /emdbed -->
 }

emdbed_example_test.go

@@ -1,3 +1,4 @@
+// Package emdbed is for embedding "things" in your markdown
 package emdbed
 
 import (

io.go

@@ -25,7 +25,15 @@ func (e emdbed) line(line int, end bool) (int, error) {
 	if len(indexes) < line {
 		return 0, fmt.Errorf("file %q has no line %d", e.name, line)
 	}
-	return indexes[line-1][0], nil
+	dec := 1
+	if !end {
+		dec++
+	}
+	var inc int
+	if !end {
+		inc++
+	}
+	return indexes[line-dec][0] + inc, nil
 }
 
 func (e emdbed) regex(pattern string, end bool) (int, error) {