add deprecation warnings throughout docs

docs/admin/Deployment-PHP.md

@@ -1,5 +1,8 @@
 # Deploying Nominatim using the PHP frontend
 
+!!! danger
+    The PHP frontend is deprecated and will be removed in Nominatim 5.0.
+
 The Nominatim API is implemented as a PHP application. The `website/` directory
 in the project directory contains the configured website. You can serve this
 in a production environment with any web server that is capable to run

docs/admin/Import.md

@@ -302,6 +302,9 @@ To run Nominatim via webservers like Apache or nginx, please continue reading
 
 #### Testing the PHP frontend
 
+!!! danger
+    The PHP fronted is deprecated and will be removed in Nominatim 5.0.
+
 You can run a small test server with the PHP frontend like this:
 
 ```sh

docs/admin/Installation.md

@@ -72,7 +72,7 @@ For running the Python frontend:
     * [starlette](https://www.starlette.io/)
   * [uvicorn](https://www.uvicorn.org/)
 
-For running the legacy PHP frontend:
+For running the legacy PHP frontend (deprecated, will be removed in Nominatim 5.0):
 
   * [PHP](https://php.net) (7.3+)
   * PHP-pgsql
@@ -194,6 +194,7 @@ sudo make install
     cmake: `cmake -DBUILD_MODULE=on ../Nominatim`. To compile the module
     you need to have the server development headers for PostgreSQL installed.
     On Ubuntu/Debian run: `sudo apt install postgresql-server-dev-<postgresql version>`
+    The legacy tokenizer is deprecated and will be removed in Nominatim 5.0
 
 
 Nominatim installs itself into `/usr/local` per default. To choose a different

docs/admin/Migration.md

@@ -1,12 +1,17 @@
 # Database Migrations
 
-Since version 3.7.0 Nominatim offers automatic migrations. Please follow
+Nominatim offers automatic migrations since version 3.7. Please follow
 the following steps:
 
-* stop any updates that are potentially running
+* Stop any updates that are potentially running
-* update Nominatim to the newer version
+* Update the backend: `pip install -U nominatim-db`
-* go to your project directory and run `nominatim admin --migrate`
+* Go to your project directory and run `nominatim admin --migrate`
-* (optionally) restart updates
+* Update the frontend: `pip install -U nominatim-api`
+* (optionally) Restart updates
+
+If you are still using CMake for the installation of Nominatim, then you
+need to update the software in one step before migrating the database.
+It is not recommended to do this while the machine is serving requests.
 
 Below you find additional migrations and hints about other structural and
 breaking changes. **Please read them before running the migration.**

docs/customize/SQLite.md

@@ -12,11 +12,16 @@ To use a SQLite database, you need to install:
 
 * SQLite (>= 3.30)
 * Spatialite (> 5.0.0)
+* aiosqlite
 
 On Ubuntu/Debian, you can run:
 
     sudo apt install sqlite3 libsqlite3-mod-spatialite libspatialite7
 
+Install the aiosqlite Python package in your virtual environment:
+
+    /srv/nominatim-venv/bin/pip install aiosqlite
+
 ## Creating a new SQLite database
 
 Nominatim cannot import directly into SQLite database. Instead you have to

docs/customize/Tokenizers.md

@@ -17,6 +17,11 @@ they can be configured.
 
 ## Legacy tokenizer
 
+!!! danger
+    The Legacy tokenizer is deprecated and will be removed in Nominatim 5.0.
+    If you still use a database with the legacy tokenizer, you must reimport
+    it using the ICU tokenizer below.
+
 The legacy tokenizer implements the analysis algorithms of older Nominatim
 versions. It uses a special Postgresql module to normalize names and queries.
 This tokenizer is automatically installed and used when upgrading an older