Update CONTRIBUTING.md (#9897)

* Update CONTRIBUTING.md

* Update CONTRIBUTING.md

docs/CONTRIBUTING.md

@@ -3,12 +3,12 @@
 
 ## Contributor License Agreement
 
-By contributing you agree to the [LICENSE](../LICENSE) of this repository.
+By contributing, you agree to the [LICENSE](../LICENSE) of this repository.
 
 
 ## Contributor Code of Conduct
 
-By contributing you agree to respect the [Code of Conduct](CODE_OF_CONDUCT.md) of this repository. ([translations](README.md#translations))
+By contributing, you agree to respect the [Code of Conduct](CODE_OF_CONDUCT.md) of this repository. ([translations](README.md#translations))
 
 
 ## In a nutshell
@@ -37,7 +37,7 @@ By contributing you agree to respect the [Code of Conduct](CODE_OF_CONDUCT.md) o
 - make sure a book is free. Double-check if needed. It helps the admins if you comment in the PR as to why you think the book is free.
 - we don't accept files hosted on Google Drive, Dropbox, Mega, Scribd, Issuu and other similar file upload platforms
 - insert your links in alphabetical order, as described [below](#alphabetical-order).
-- use the link with the most authoritative source (meaning the author's website is better than the editor's website, which is better than a third party website)
+- use the link with the most authoritative source (meaning the author's website is better than the editor's website, which is better than a third-party website)
     - no file hosting services (this includes (but is not limited to) Dropbox and Google Drive links)
 - always prefer a `https` link over a `http` one -- as long as they are on the same domain and serve the same content
 - on root domains, strip the trailing slash: `http://example.com` instead of `http://example.com/`
@@ -48,9 +48,9 @@ By contributing you agree to respect the [Code of Conduct](CODE_OF_CONDUCT.md) o
     1. *replace it* with its `http` counterpart if possible (because accepting exceptions can be complicated on mobile devices).
     2. *leave it* if no `http` version is available but the link is still accessible through `https` by adding an exception to the browser or ignoring the warning.
     3. *remove it* otherwise.
-- if a link exists in multiple format, add a separate link with a note about each format
+- if a link exists in multiple formats, add a separate link with a note about each format
 - if a resource exists at different places on the Internet
-    - use the link with the most authoritative source (meaning author's website is better than editor's website is better than third party website)
+    - use the link with the most authoritative source (meaning author's website is better than editor's website is better than third-party website)
     - if they link to different editions, and you judge these editions are different enough to be worth keeping them, add a separate link with a note about each edition (see [Issue #2353](https://github.com/EbookFoundation/free-programming-books/issues/2353) to contribute to the discussion on formatting).
 - prefer atomic commits (one commit by addition/deletion/modification) over bigger commits. No need to squash your commits before submitting a PR. (We will never enforce this rule as it's just a matter of convenience for the maintainers)
 - if the book is older, include the publication date with the title.
@@ -201,7 +201,7 @@ Our lists provide a minimal set of metadata: titles, URLs, creators, platforms,
 
 ##### Platforms and Access Notes
 
-- Courses. Especially for our course lists, the platform is an important part of the resource description. This is because course platforms have different affordances and access models. While we usually won't list a book that requires a registration, many course platforms have affordances that don't work without some sort of account. Example course platforms include Coursera, EdX, Udacity, and Udemy. When a course depends on a platform, the platform name should be listed in parentheses.
+- Courses. Especially for our course lists, the platform is an important part of the resource description. This is because course platforms have different affordances and access models. While we usually won't list a book that requires registration, many course platforms have affordances that don't work without some sort of account. Example course platforms include Coursera, EdX, Udacity, and Udemy. When a course depends on a platform, the platform name should be listed in parentheses.
 - YouTube. We have many courses which consist of YouTube playlists. We do not list YouTube as a platform, we try to list the YouTube creator, which is often a sub-platform.
 - YouTube videos. We usually don't link to individual YouTube videos unless they are more than an hour long and are structured like a course or a tutorial. If this is the case, be sure to make a note of it in the PR description.
 - No shortened (i.e. youtu.be/xxxx) links!
@@ -249,7 +249,7 @@ There are lots of books that we list that don't have these attributes; it can de
 
 Sometimes these can be hard to distinguish!
 
-Courses often have associated textbooks, which we would list in our books lists. Courses have lectures, exercises, tests, notes or other didactic aids. A single lecture or video by itself is not a course. A powerpoint is not a course.
+Courses often have associated textbooks, which we would list in our books lists. Courses have lectures, exercises, tests, notes or other didactic aids. A single lecture or video by itself is not a course. A PowerPoint is not a course.
 
 
 ##### Interactive Tutorials vs. Other stuff