Fix README typo about ignoring issues (#129)

* Fix README typo

It said specified issues, now it's one of the specified labels.

* Fix docs/CONCEPT.md typo

Author: David Sevilla Martín

README.md

@@ -71,7 +71,7 @@ In order to have spliendid generated release notes, we reccomend to follow these
 
 1. Start the title with a verb (e.g. Change header styles)
 2. Use the imperative mood in the title (e.g. Fix, not Fixed or Fixes header styles)
-3. Use labels wisely and assign one label per issue. `gren` has the [option to ignore issues](https://github-tools.github.io/github-release-notes/options.html#ignore-issues-with) that have a specified issues.
+3. Use labels wisely and assign one label per issue. `gren` has the [option to ignore issues](https://github-tools.github.io/github-release-notes/options.html#ignore-issues-with) that have one of the specified labels.
 
 ### `commits`
 

docs/concept.md

@@ -66,7 +66,7 @@ In order to have spliendid generated release notes, we reccomend to follow these
 
 1. Start the title with a verb (e.g. Change header styles)
 2. Use the imperative mood in the title (e.g. Fix, not Fixed or Fixes header styles)
-3. Use labels wisely and assign one label per issue. `gren` has the [option to ignore issues](https://github-tools.github.io/github-release-notes/options.html#ignore-issues-with) that have a specified issues.
+3. Use labels wisely and assign one label per issue. `gren` has the [option to ignore issues](https://github-tools.github.io/github-release-notes/options.html#ignore-issues-with) that have a one of the specified labels.
 
 ### `commits`