[TASK] Link to next instructions for Legacy Install section (#380)

* [TASK] Link to next instructions for Legacy Install section

Adds a link from the end of the Legacy Install instructions to the "Access TYPO3 via a web browser" step in the standard instructions.

Also adds a warning admonition to the text about the Legacy Install instructions being out of date.

* [TASK] Fix references

* [BUGFIX] Fix references

---------

Co-authored-by: lina.wolf <lwolf@w-commerce.de>

(cherry picked from commit 5dc7b74)

Documentation/Installation/Install.rst

@@ -121,6 +121,8 @@ Create an empty file called `FIRST_INSTALL` in the `/public` directory:
  ├── var
  └── vendor
 
+.. _install-access-typo3-via-a-web-browser:
+
 Access TYPO3 via a web browser
 ------------------------------
 

Documentation/Installation/LegacyInstallation.rst

@@ -8,8 +8,10 @@
 Legacy Installation
 ===================
 
-This guide details how TYPO3 can be installed without using Composer. This method of installation
-is now considered out of date, users are strongly encouraged to use the Composer based :ref:`install`
+.. warning::
+ This guide details how TYPO3 can be installed without using Composer. This method of installation
+ is now considered **out of date**, users are strongly encouraged to use the
+ :ref:`Composer-based installation instructions <install>`.
 
 Installing on a Unix Server
 ===========================
@@ -81,8 +83,10 @@ Installing on a Windows Server
 Completing The Installation
 ===========================
 
-After the source package has been extracted and the symlinks created,
-visit the Access TYPO3 via web browser to complete the installation.
+After the source package has been extracted and the symlinks created, continue from the
+:ref:`Access TYPO3 via a web browser <install-access-typo3-via-a-web-browser>`
+section of the :ref:`instructions for installing TYPO3 using Composer <install>` to
+complete the installation.
 
 .. toctree::
  :hidden: