Fix grammar and punctuation in CONTRIBUTING md

diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
index aea8b30b908eb569223ea2d9b82207ee19577ba0..8a4e29603efe88afca077ae324c097ffb4fee49b 100644 (file)
--- a/CONTRIBUTING.md
+++ b/CONTRIBUTING.md
@@ -87,7 +87,7 @@ and why it should be the way it is.
 
 ## i18n
 
-If you make a change that involve the locale files (in `config/locales`) then please
+If you make a change that involves the locale files (in `config/locales`) then please
 only submit changes to the `en.yml` file. The other files are updated via
 [Translatewiki](https://translatewiki.net/wiki/Translating:OpenStreetMap) and should
 not be included in your pull request.
@@ -143,7 +143,7 @@ with making the reviews as straightforward as possible:
   large to review in one sitting, or if changes are requested, then the
   maintainer needs to repeatedly re-read code that has already been considered.
 * The commit history is important. This is a large codebase, developed over many
-  years by many developers. We frequently need to read the commit history (e.g.
+  years by many developers. We frequently need to read the commit history (e.g.,
   using `git blame`) to figure out what is going on. So small, understandable,
   and relevant commits are important for other developers looking back at your
   work in future.