docs: Indicate latest Zulip version in installation and upgrade docs.

With copy-editing from tabbott, and also a migration to use
LATEST_RELEASE_VERSION, which will be correct even on the /latest/
paths.

Fixes #19695.

(cherry picked from commit 3b1cb0b25a)

docs/conf.py

@@ -20,7 +20,7 @@ from typing import Any, Dict, Optional
 # sys.path.insert(0, os.path.abspath('.'))
 
 sys.path.insert(0, os.path.abspath(os.path.join(os.path.dirname(__file__), "..")))
-from version import ZULIP_VERSION
+from version import LATEST_RELEASE_VERSION, ZULIP_VERSION
 
 # -- General configuration ------------------------------------------------
 
@@ -36,6 +36,7 @@ extensions = [
 
 myst_enable_extensions = [
     "colon_fence",
+    "substitution",
 ]
 
 # Add any paths that contain templates here, relative to this directory.
@@ -105,6 +106,10 @@ pygments_style = "sphinx"
 # If true, `todo` and `todoList` produce output, else they produce nothing.
 todo_include_todos = False
 
+myst_substitutions = {
+    "LATEST_RELEASE_VERSION": LATEST_RELEASE_VERSION,
+}
+
 
 # -- Options for HTML output ----------------------------------------------
 

docs/production/install.md

@@ -14,9 +14,9 @@ you can create a test organization at <https://zulip.com/new>.
 
 ## Step 1: Download the latest release
 
-Download and unpack [the latest built server
-tarball](https://download.zulip.com/server/zulip-server-latest.tar.gz)
-with the following commands:
+Download and unpack [the latest server
+release](https://download.zulip.com/server/zulip-server-latest.tar.gz)
+(**Zulip Server {{ LATEST_RELEASE_VERSION }}**) with the following commands:
 
 ```bash
 cd $(mktemp -d)

docs/production/upgrade-or-modify.md

@@ -24,8 +24,9 @@ to a new Zulip release:
    for all releases newer than what is currently installed.
 
 1. Download the appropriate release tarball from
-   <https://download.zulip.com/server/> You can download the latest
-   release with:
+   <https://download.zulip.com/server/>. You can get the latest
+   release (**Zulip Server {{ LATEST_RELEASE_VERSION }}**) with the
+   following command:
 
    ```bash
    wget https://download.zulip.com/server/zulip-server-latest.tar.gz
@@ -40,7 +41,7 @@ to a new Zulip release:
 1. Log in to your Zulip and run as root:
 
    ```bash
-   /home/zulip/deployments/current/scripts/upgrade-zulip zulip-server-VERSION.tar.gz
+   /home/zulip/deployments/current/scripts/upgrade-zulip zulip-server-latest.tar.gz
    ```
 
    The upgrade process will: