fix some broken links

_posts/2013-03-20-gsoc13.md

@@ -333,7 +333,7 @@ will benefit from your contributions.
 
 2. Port the plugin to Python 3.3 and Sublime Text 3, possibly taking advantage of the features introduced in the new version. A guide can be found on the [Sublime Text 3 webpage](https://www.sublimetext.com/docs/3/porting_guide.html). There's also the ST3 branch, which has already ported a bulk of functionality.
 
-3. Create a [github (markdown](https://help.github.com/articles/github-flavored-markdown)) for the project detailing the plugin installation and usage and a screencast of using the new plugin.
+3. Create a GitHub-flavored-Markdown file for the project detailing the plugin installation and usage and a screencast of using the new plugin.
 
 Before applying, please choose one of the bugs in the current plugin ([https://github.com/sublimescala/sublime-ensime/issues?state=open](https://github.com/sublimescala/sublime-ensime/issues?state=open)) and try to fix it, so you see how the plugin works. We do accept partial fixes and simple workarounds, but please do try to fix it yourself.
 

blog/_posts/2017-08-28-gsoc-connecting-contributors-with-projects.md

@@ -41,7 +41,7 @@ Here's some more info about how each piece of contributing info gets set:
 
 As an example, the [Scaladex project](https://github.com/scalacenter/scaladex) (for the code behind the website) uses the label "low-hanging fruit" to mark beginner-friendly issues in Github so this label can be set by the maintainer in the edit project page and all the [issues with this label](https://github.com/scalacenter/scaladex/labels/low-hanging%20fruit) will be stored for this project. It also has a [gitter room](https://gitter.im/scalacenter/scaladex) for chatting and a [contributing guide](https://github.com/scalacenter/scaladex/blob/master/CONTRIBUTING.md) which will be auto-populated for the project when all the projects are indexed.
 
-Scaladex uses Github's [GraphQL API](https://developer.github.com/v4/) to get a project's beginner-friendly issues, see the [Github Topics](#github-topics) section below for more info about Github's GraphQL API. To get a project's contributing guide, Scaladex uses Github's [REST API](https://developer.github.com/v3/) to send a GET request to the [Community Profile API](https://developer.github.com/v3/repos/community/) which will return links to a project's contributing guide, code of conduct and license. Lastly, to get a project's chatroom, Scaladex generates a URL for a project's gitter room based on the project's repository name and the organization it belongs to (Ex. <https://gitter.im/scalacenter/scaladex>) and checks if that URL exists.
+Scaladex uses Github's GraphQL API to get a project's beginner-friendly issues, see the [Github Topics](#github-topics) section below for more info about Github's GraphQL API. To get a project's contributing guide, Scaladex uses Github's REST API to send a GET request to the Community Profile API which will return links to a project's contributing guide, code of conduct and license. Lastly, to get a project's chatroom, Scaladex generates a URL for a project's gitter room based on the project's repository name and the organization it belongs to (Ex. <https://gitter.im/scalacenter/scaladex>) and checks if that URL exists.
 
 You can also find Contributing Info on the front page of Scaladex. Now, Scaladex highlights a random subset of projects which have Contributing Info on the front page of Scaladex. It picks a random selection of projects each time the page is loaded to give the same amount of exposure to all projects with Contributing Info. We hope to highlight and better guide potential contributors to projects and issues that are of interest to them!
 

blog/_posts/2018-06-04-scalac-profiling.md

@@ -437,7 +437,7 @@ data.
 
 To generate a flamegraph, clone
 [scalacenter/scalac-profiling](https://github.com/scalacenter/scalac-profiling),
-`cd` into `FlameGraph`, `git submodule update --init` (note that this command will require you to have [ssh authentication configured with your GitHub account](https://help.github.com/articles/connecting-to-github-with-ssh/)) and run the following
+`cd` into `FlameGraph`, `git submodule update --init` (note that this command will require you to have [ssh authentication configured with your GitHub account](https://docs.github.com/en/authentication/connecting-to-github-with-ssh)) and run the following
 script in the repository:
 
 ```bash

community/index.md

@@ -201,4 +201,4 @@ The [Phil Bagwell Memorial Scala Community Award](./phil-bagwell-award.html) is
 
 Read-only archives of these retired groups remain available.
 
- * [scala-user](https://groups.google.com/group/scala-user), [scala-announce](https://groups.google.com/group/scala-announce), [scala-language](https://groups.google.com/group/scala-language), [scala-debate](https://groups.google.com/group/scala-debate), [scala-internals](https://groups.google.com/group/scala-internals), [scala-tools](https://groups.google.com/group/scala-tools), [scala-sips](https://groups.google.com/group/scala-sips)
+ * [scala-user](https://groups.google.com/g/scala-user), [scala-announce](https://groups.google.com/g/scala-announce), [scala-language](https://groups.google.com/g/scala-language), [scala-debate](https://groups.google.com/g/scala-debate), [scala-internals](https://groups.google.com/g/scala-internals), [scala-tools](https://groups.google.com/g/scala-tools), [scala-sips](https://groups.google.com/g/scala-sips)