docs: broken links and typos (#6676)

Co-authored-by: repo-ranger[bot] <39074581+repo-ranger[bot]@users.noreply.github.com>

README.md

@@ -96,8 +96,8 @@ You can read a [tutorial on how to add a badge][tutorial].
 [![GitHub issues by-label](https://img.shields.io/github/issues/badges/shields/good%20first%20issue)](https://github.com/badges/shields/issues?q=is%3Aissue+is%3Aopen+label%3A%22good+first+issue%22)
 
 [service-tests]: https://github.com/badges/shields/blob/master/doc/service-tests.md
-[tutorial]: doc/TUTORIAL.md
-[contributing]: CONTRIBUTING.md
+[tutorial]: https://github.com/badges/shields/blob/master/doc/TUTORIAL.md
+[contributing]: https://github.com/badges/shields/blob/master/CONTRIBUTING.md
 
 ## Development
 
@@ -142,9 +142,9 @@ Daily tests, including a full run of the service tests and overall code coverage
 [gitpod]: https://www.gitpod.io/
 [snapshot tests]: https://glebbahmutov.com/blog/snapshot-testing/
 [prometheus]: https://prometheus.io/
-[prometheus configuration]: doc/self-hosting.md#prometheus
+[prometheus configuration]: https://github.com/badges/shields/blob/master/doc/self-hosting.md#prometheus
 [sentry]: https://sentry.io/
-[sentry configuration]: doc/self-hosting.md#sentry
+[sentry configuration]: https://github.com/badges/shields/blob/master/doc/self-hosting.md#sentry
 [daily-tests]: https://github.com/badges/daily-tests
 [nodemon]: https://nodemon.io/
 [nodemon debug]: https://github.com/Microsoft/vscode-recipes/tree/master/nodemon
@@ -154,7 +154,7 @@ Daily tests, including a full run of the service tests and overall code coverage
 
 There is documentation about [hosting your own server][self-hosting].
 
-[self-hosting]: doc/self-hosting.md
+[self-hosting]: https://github.com/badges/shields/blob/master/doc/self-hosting.md
 
 ## History
 
@@ -179,8 +179,8 @@ You can read more about [the project's inception][thread],
 [olivierlacan]: https://github.com/olivierlacan
 [espadrine]: https://github.com/espadrine
 [old-gh-badges]: https://github.com/badges/gh-badges
-[motivation]: spec/motivation.md
-[spec]: spec/SPECIFICATION.md
+[motivation]: https://github.com/badges/shields/blob/master/spec/motivation.md
+[spec]: https://github.com/badges/shields/blob/master/spec/SPECIFICATION.md
 [thread]: https://github.com/h5bp/lazyweb-requests/issues/150
 
 ## Project leaders

doc/TUTORIAL.md

@@ -21,7 +21,7 @@ Please [improve the tutorial](https://github.com/badges/shields/edit/master/doc/
 
 You should have [git](https://git-scm.com/) installed.
 If you do not, [install git](https://www.linode.com/docs/development/version-control/how-to-install-git-on-linux-mac-and-windows/)
-and learn about the [Github workflow](http://try.github.io/).
+and learn about the [GitHub workflow](http://try.github.io/).
 
 #### Node, NPM
 

doc/server-secrets.md

@@ -121,12 +121,12 @@ Drone instance and obtain a token from the user profile page.
 - `GITHUB_URL` (yml: `public.services.github.baseUri`)
 - `GH_TOKEN` (yml: `private.gh_token`)
 
-Because of Github rate limits, you will need to provide a token, or else badges
+Because of GitHub rate limits, you will need to provide a token, or else badges
 will stop working once you hit 60 requests per hour, the
 [unauthenticated rate limit][github rate limit].
 
 You can [create a personal access token][personal access tokens] through the
-Github website. When you create the token, you can choose to give read access
+GitHub website. When you create the token, you can choose to give read access
 to your repositories. If you do that, your self-hosted Shields installation
 will have access to your private repositories.