[boot-to-talos] Introduce simple kexec mode

Signed-off-by: Andrei Kvapil <kvapss@gmail.com>

Author: kvaps

content/en/docs/install/talos/_index.md

@@ -25,8 +25,6 @@ They have various limitations and optimal use cases:
     a simple installation method, which can be used completely from userspace, and with no external dependencies except the Talos image.
 
     Choose this option if you are new to Talos or if you have VMs with pre-installed OS from a cloud provider.
--   [Boot to Talos Linux from another Linux OS using `kexec`]({{% ref "/docs/install/talos/kexec" %}}) — another simple installation method,
-    but with some extra requirements. 
 -   [Install using temporary DHCP and PXE servers running in Docker containers]({{% ref "/docs/install/talos/pxe" %}}) — 
     requires an extra management machine, but allows for installing on multiple hosts at once.
 -   [Install using ISO image]({{% ref "/docs/install/talos/iso" %}}) — optimal for systems which can automate ISO installation.

content/en/docs/install/talos/boot-to-talos.md

@@ -3,6 +3,8 @@ title: "Install Talos Linux using boot-to-talos"
 linkTitle: boot-to-talos
 description: "Install Talos Linux using boot-to-talos, a convenient CLI application requiring nothing but a Talos image."
 weight: 5
+aliases:
+  - /docs/talos/install/kexec
 ---
 
 This guide explains how to install Talos Linux on a host running any other Linux distribution using `boot-to-talos`.
@@ -12,6 +14,17 @@ It works entirely from userspace and has no external dependencies except the Tal
 
 Note that Cozystack provides its own Talos builds, which are tested and optimized for running a Cozystack cluster.
 
+## Modes
+
+`boot-to-talos` supports two installation modes:
+
+1. **boot** – Extract the kernel and initrd from the Talos installer and boot them directly using the kexec mechanism.
+2. **install** – Prepare the environment, run the Talos installer, and then overwrite the system disk with the installed image.
+
+{{< note >}}
+If one mode doesn't work on your system, try the other. Different methods may work better on different operating systems.
+{{< /note >}}
+
 ## Installation
 
 ### 1. Install `boot-to-talos`
@@ -35,7 +48,10 @@ Make sure to use Cozystack's own Talos build, found at [ghcr.io/cozystack/cozyst
 
 
 ```console
-$ boot-to-talos
+Mode:
+  1. boot – extract the kernel and initrd from the Talos installer and boot them directly using the kexec mechanism.
+  2. install – prepare the environment, run the Talos installer, and then overwrite the system disk with the installed image.
+Mode [1]: 2
 Target disk [/dev/sda]:
 Talos installer image [ghcr.io/cozystack/cozystack/talos:v1.10.5]:
 Add networking configuration? [yes]:
@@ -97,7 +113,25 @@ There are builds for several architectures:
 
 Understanding these steps is not required to install Talos Linux.
 
-`boot-to-talos` performs a series of steps after it receives the configuration values: 
+The workflow depends on the selected mode:
+
+#### Boot Mode
+
+When using the **boot** mode, `boot-to-talos` performs the following steps:
+
+1.  **Unpacks Talos installer in RAM**<br>
+    Extracts layers from the Talos‑installer container into a throw‑away `tmpfs`.
+    Note that Docker is not needed during this step.
+2.  **Extracts kernel and initrd**<br>
+    Extracts the kernel (`vmlinuz`) and initial ramdisk (`initramfs.xz`) from the Talos installer image.
+3.  **Loads kernel via kexec**<br>
+    Uses the `kexec` system call to load the Talos kernel and initrd into memory with the provided kernel command line parameters.
+4.  **Reboots into Talos**<br>
+    Executes `kexec --exec` to switch to the Talos kernel without a physical reboot. After booting, you can apply Talos configuration to complete the installation.
+
+#### Install Mode
+
+When using the **install** mode, `boot-to-talos` performs the following steps:
 
 1.  **Unpacks Talos installer in RAM**<br>
     Extracts layers from the Talos‑installer container into a throw‑away `tmpfs`.