docs: replace "Github" with "GitHub"

This the way GitHub refer to themselves.

CONTRIBUTING.md

@@ -21,14 +21,14 @@ with the [latest beta of rclone](https://beta.rclone.org/):
 ## Submitting a pull request ##
 
 If you find a bug that you'd like to fix, or a new feature that you'd
-like to implement then please submit a pull request via Github.
+like to implement then please submit a pull request via GitHub.
 
 If it is a big feature then make an issue first so it can be discussed.
 
 You'll need a Go environment set up with GOPATH set.  See [the Go
 getting started docs](https://golang.org/doc/install) for more info.
 
-First in your web browser press the fork button on [rclone's Github
+First in your web browser press the fork button on [rclone's GitHub
 page](https://github.com/ncw/rclone).
 
 Now in your terminal
@@ -74,13 +74,13 @@ When you are done with that
 
     git push origin my-new-feature
 
-Go to the Github website and click [Create pull
+Go to the GitHub website and click [Create pull
 request](https://help.github.com/articles/creating-a-pull-request/).
 
 You patch will get reviewed and you might get asked to fix some stuff.
 
 If so, then make the changes in the same branch, squash the commits,
-rebase it to master then push it to Github with `--force`.
+rebase it to master then push it to GitHub with `--force`.
 
 ## Enabling CI for your fork ##
 
@@ -358,7 +358,7 @@ See the [testing](#testing) section for more information on integration tests.
 
 Add your fs to the docs - you'll need to pick an icon for it from [fontawesome](http://fontawesome.io/icons/).  Keep lists of remotes in alphabetical order but with the local file system last.
 
-  * `README.md` - main Github page
+  * `README.md` - main GitHub page
   * `docs/content/remote.md` - main docs page (note the backend options are automatically added to this file with `make backenddocs`)
   * `docs/content/overview.md` - overview docs
   * `docs/content/docs.md` - list of remotes in config section

MAINTAINERS.md

@@ -58,7 +58,7 @@ Close tickets as soon as you can - make sure they are tagged with a release.  Po
 
 Try to process pull requests promptly!
 
-Merging pull requests on Github itself works quite well now-a-days so you can squash and rebase or rebase pull requests.  rclone doesn't use merge commits.  Use the squash and rebase option if you need to edit the commit message.
+Merging pull requests on GitHub itself works quite well now-a-days so you can squash and rebase or rebase pull requests.  rclone doesn't use merge commits.  Use the squash and rebase option if you need to edit the commit message.
 
 After merging the commit, in your local master branch, do `git pull` then run `bin/update-authors.py` to update the authors file then `git push`.
 

MANUAL.md

@@ -61,7 +61,7 @@ Features
 Links
 
   * [Home page](https://rclone.org/)
-  * [Github project page for source and bug tracker](https://github.com/ncw/rclone)
+  * [GitHub project page for source and bug tracker](https://github.com/ncw/rclone)
   * [Rclone Forum](https://forum.rclone.org)
   * <a href="https://google.com/+RcloneOrg" rel="publisher">Google+ page</a>
   * [Downloads](https://rclone.org/downloads/)

docs/content/about.md

@@ -66,7 +66,7 @@ Features
 Links
 
   * <i class="fa fa-home"></i> [Home page](https://rclone.org/)
-  * <i class="fa fa-github"></i> [Github project page for source and bug tracker](https://github.com/ncw/rclone)
+  * <i class="fa fa-github"></i> [GitHub project page for source and bug tracker](https://github.com/ncw/rclone)
   * <i class="fa fa-comments"></i> [Rclone Forum](https://forum.rclone.org)
   * <i class="fa fa-google-plus"></i> <a href="https://google.com/+RcloneOrg" rel="publisher">Google+ page</a>
   * <i class="fa fa-cloud-download"></i>[Downloads](/downloads/)