docs: fix broken link

README.md

@@ -28,8 +28,13 @@ What is the Tool Registry API Schema?
 
 This is the home of the schema for the GA4GH Tool Registry API. The GA4GH Tool Registry API is a standard for listing and describing available tools (both stand-alone, self-contained tools and workflows in CWL, WDL, Nextflow, Galaxy or Snakemake) in a given registry. This defines a minimal, common API describing tools that we propose for support by multiple tool/workflow registries like [Dockstore](https://www.dockstore.org/), [BioContainers](https://biocontainers.pro), and [Agora](https://github.com/broadinstitute/agora) for the purposes of exchange, indexing, and searching.
 
-This repo uses the [HubFlow](https://datasift.github.io/gitflow/) scheme which is closely based on [GitFlow](https://nvie.com/posts/a-successful-git-branching-model/). In practice, this means that the master branch contains the last production release of the schema whereas the develop branch contains the latest development changes which will end up in the next production release. 
-As of February 2022,  the master branch contains the last production release (currently ![release_badge](https://img.shields.io/github/v/tag/ga4gh/tool-registry-service-schemas))) whereas the develop branch contains work which will accumulate and evolve into a 2.1 production release.
+This repo uses the [HubFlow](https://github.com/mvalipour/hubflow) scheme which is closely based on 
+[GitFlow](https://nvie.com/posts/a-successful-git-branching-model/). In practice, this means that 
+the master branch contains the last production release of the schema whereas the develop branch 
+contains the latest development changes which will end up in the next production release. As of 
+February 2022,  the master branch contains the last production release (currently 
+![release_badge](https://img.shields.io/github/v/tag/ga4gh/tool-registry-service-schemas))) whereas 
+the develop branch contains work which will accumulate and evolve into a 2.1 production release.
 
 Our current iteration focuses on a read-only API due to potentially different views and approaches to registration/security.
 
@@ -98,4 +103,4 @@ For more information
   * [WES](https://github.com/ga4gh/wiki/wiki/Workflow-Execution-Service)
 * [Global Alliance for Genomics and Health](https://www.ga4gh.org/) - GA4GH's main page
 * [GA4GH Technical Alignment Sub Committee (TASC)](https://github.com/ga4gh/TASC) - we try to co-ordinate GA4GH API decisions here
-* [GA4GH Slack](https://ga4gh.slack.com/) - although you may need an invitation from a GA4GH administrator if your email domain name has not been allow-listed, see [https://github.com/ga4gh/TASC/issues/44](https://github.com/ga4gh/TASC/issues/44)
+* [GA4GH Slack](https://ga4gh.slack.com/) - although you may need an invitation from a GA4GH administrator if your email domain name has not been allow-listed, see [https://github.com/ga4gh/TASC/issues/44](https://github.com/ga4gh/TASC/issues/44)