Docs: correct stale references in the language-addition guide

Four items in .serena/memories/adding_new_language_support_guide.md are
wrong against the current source. Two are references that no longer
resolve:

- the subprocess helper lives at solidlsp.util.subprocess_util and is a
  module-level function, not a method on a class; the guide named
  solidlsp.utils.subprocess_utils, which does not exist
- pytest markers are declared under [tool.pytest.ini_options].markers in
  pyproject.toml; there is no pytest.ini in the repository

and two are formatting defects:

- the Documentation section used "### 5" while every other step uses
  "## Step N:", so it nested under Step 4 in rendered output
- a stray double colon in the "Implementation Pointers" label

Promoting Documentation to a top-level step also completes the Overview
list, which stopped at four.

Step 5 gains src/serena/resources/project.template.yml, which the
checklist omitted even though a new language server has to appear in its
commented list. The instruction uses `uv run` because the script imports
solidlsp and fails under an ambient interpreter, and it notes the
trailing spaces the script pads each line with, which the committed list
does not carry.

.serena/memories/adding_new_language_support_guide.md

@@ -10,6 +10,7 @@ Adding a new language involves:
 2. **Language Registration** - Adding the language to enums and configurations  
 3. **Test Repository** - Creating a minimal test project
 4. **Test Suite** - Writing comprehensive tests
+5. **Documentation** - Updating the user-facing language lists and the changelog
 
 ## Step 1: Language Server Implementation
 
@@ -59,9 +60,9 @@ To implement a new language server using the DependencyProvider pattern:
   - Implement `create_launch_command()` directly (note: no automatic support for user-level launch command overrides in this case)
   - Reference implementations: `EclipseJDTLS`, `CSharpLanguageServer`, `MatlabLanguageServer`
 
-**Implementation Pointers::**
+**Implementation Pointers:**
   - Override `create_launch_command_env` if the launch command needs environment variables to be set (defaults to `{}` in the base implementation)
-  - When calling subprocesses, e.g. to install dependencies, do not use `subprocess.run` directly; instead, use the `subprocess_run` helper method from `solidlsp.utils.subprocess_utils`
+  - When calling subprocesses, e.g. to install dependencies, do not use `subprocess.run` directly; instead, use the `subprocess_run` helper function from `solidlsp.util.subprocess_util`
 
 You should look at at least one existing implementation of each base class to understand how they work.
 
@@ -208,13 +209,14 @@ You should at least test:
 3. Finding cross-file references
 
 Have a look at `test/solidlsp/php/test_php_basic.py` as an example for what should be tested.
-Don't forget to add a new language marker to `pytest.ini`.
+Declare the new language marker under `[tool.pytest.ini_options].markers` in `pyproject.toml`.
 
 
-### 5 Documentation
+## Step 5: Documentation
 
 Update:
 
 - **README.md** - Add language to the list of languages
 - **docs/01-about/020_programming-languages.md** - Add language to the list and mention any special notes, compatibility or requirements (e.g. installations the user is required to do)
+- **src/serena/resources/project.template.yml** - Refresh the commented language-server list: run `uv run python scripts/print_language_list.py` and paste its output over the existing list, stripping the trailing spaces the script pads each line with
 - **CHANGELOG.md** - Document the new language support