Merge branch 'link-to-install' into 'master'

Link source installation instructions in README.md

See merge request https://gitlab.com/gitlab-org/gitlab/-/merge_requests/183810



Merged-by: Achilleas Pipinellis <axil@gitlab.com>
Approved-by: Achilleas Pipinellis <axil@gitlab.com>
Approved-by: Kushal Pandya <kushal@gitlab.com>
Reviewed-by: Achilleas Pipinellis <axil@gitlab.com>
Co-authored-by: Anatoli Babenia <anatoli@rainforce.org>

README.md

@@ -56,7 +56,7 @@ Please see the [requirements documentation](doc/install/requirements.md) for sys
 ## Installation
 
 The recommended way to install GitLab is with the [Omnibus packages](https://about.gitlab.com/downloads/) on our package server.
-Compared to an installation from source, this is faster and less error prone.
+Compared to [a self-compiled installation](https://docs.gitlab.com/install/installation/), this is faster and less error prone.
 Just select your operating system, download the respective package (Debian or RPM) and install it using the system's package manager.
 
 There are various other options to install GitLab, please refer to the [installation page on the GitLab website](https://about.gitlab.com/installation/) for more information.
@@ -67,8 +67,8 @@ GitLab is an open source project and we are very happy to accept community contr
 
 ## Install a development environment
 
-To work on GitLab itself, we recommend setting up your development environment with [the GitLab Development Kit](https://gitlab.com/gitlab-org/gitlab-development-kit).
-If you do not use the GitLab Development Kit you need to install and configure all the dependencies yourself, this is a lot of work and error prone.
+To work on GitLab itself, we recommend setting up your development environment with [the GitLab Development Kit (GDK)](https://gitlab.com/gitlab-org/gitlab-development-kit).
+If you do not use GDK, you need to [install and configure all the dependencies yourself](https://docs.gitlab.com/install/installation/), this is a lot of work and error prone.
 One small thing you also have to do when installing it yourself is to copy the example development Puma configuration file:
 
 ```shell