sagemathgh-38581: README.md, src/doc/en/installation: Replace release…

… tours links

    
<!-- ^ Please provide a concise and informative title. -->
<!-- ^ Don't put issue numbers in the title, do this in the PR
description below. -->
<!-- ^ For example, instead of "Fixes sagemath#12345" use "Introduce new method
to calculate 1 + 2". -->
<!-- v Describe your changes below in detail. -->
<!-- v Why is this change required? What problem does it solve? -->
<!-- v If this PR resolves an open issue, please link to it here. For
example, "Fixes sagemath#12345". -->

The release tours are now accessed through GitHub Releases.

This is the next step of:
- sagemath#31533

### 📝 Checklist

<!-- Put an `x` in all the boxes that apply. -->

- [x] The title is concise and informative.
- [x] The description explains in detail what this PR is about.
- [x] I have linked a relevant issue or discussion.
- [ ] I have created tests covering the changes.
- [ ] I have updated the documentation and checked the documentation
preview.

### ⌛ Dependencies

<!-- List all open PRs that this PR logically depends on. For example,
-->
<!-- - sagemath#12345: short description why this is a dependency -->
<!-- - sagemath#34567: ... -->
    
URL: sagemath#38581
Reported by: Matthias Köppe
Reviewer(s): Kwankyu Lee

README.md

@@ -69,7 +69,7 @@ virtualization).
 
 Detailed information on supported platforms for a specific version of Sage
 can be found in the section _Availability and installation help_ of the
-[release tour](https://wiki.sagemath.org/ReleaseTours) for this version.
+[release tour for this version](https://github.com/sagemath/sage/releases).
 
 We highly appreciate contributions to Sage that fix portability bugs
 and help port Sage to new platforms; let us know at the [sage-devel
@@ -489,8 +489,8 @@ Troubleshooting
 ---------------
 
 If you have problems building Sage, check the Sage Installation Guide,
-as well as the version-specific Sage Installation FAQ in the [Sage Release
-Tour](https://wiki.sagemath.org/ReleaseTours) corresponding to the
+as well as the version-specific installation help in the [release
+tour](https://github.com/sagemath/sage/releases) corresponding to the
 version that you are installing.
 
 Please do not hesitate to ask for help in the [SageMath forum

src/doc/en/installation/index.rst

@@ -11,8 +11,7 @@ was made.
 More up-to-date information and details regarding supported platforms
 may have become available afterwards and can be found in the section
 "Availability and installation help" of the
-`release tour <https://wiki.sagemath.org/ReleaseTours>`_ for each
-SageMath release.
+`release tour for each SageMath release <https://github.com/sagemath/sage/releases>`_.
 
 **Where would you like to run SageMath?** Pick one of the following sections.
 

src/doc/en/installation/troubles.rst

@@ -8,8 +8,8 @@ the :ref:`sec-installation-from-sources` or use one of the alternatives
 proposed at the end of :ref:`installation-guide`.
 
 If you have any problems building or running Sage, please take a look
-at the Installation FAQ in the `Sage Release Tour
-<https://wiki.sagemath.org/ReleaseTours>`_ corresponding to the version
+at the `release tour
+<https://github.com/sagemath/sage/releases>`_ corresponding to the version
 that you are installing.  It may offer version-specific installation
 help that has become available after the release was made and is
 therefore not covered by this manual.