docs: add the 4 missing screenshots to "How to Create a Presentation Template"

[nicolasiscoding]

docs/TurboDocx Templating/How to Create a Presentation Template.md has 4 Screenshots Coming Soon placeholders, one per step. Replace each with a real screenshot.

Where each screenshot comes from

PowerPoint (desktop) — must be captured manually; not browser-automatable:

• Step 1 — Create New Presentation Template: a slide with content + areas left for dynamic content.
• Step 2 — Setting Up Variables in Slides: the invisible-shape technique — Insert → Shape, type {WhatWeHeard}, Shape Format → Align Text → Top, Shape Fill/Outline → No Fill. Instructions are PowerPoint-ribbon-specific, so shots should be from PowerPoint (not Google Slides).

TurboDocx web app — automatable with the doc-screenshotter skill:

• Step 3 — Upload Presentation Template: Templates → New Template → the Upload area (drag-and-drop the .pptx).
• Step 4 — Preview Template: the preview screen showing detected variables + the Create Template button.

Notes

• Steps 3 & 4 need a sample .pptx containing bracket variables in invisible shapes (e.g. {WhatWeHeard}, {HowWeCanHelp}, {FollowUpQuestions}) to upload.
• Match the existing convention: save to static/img/<doc_slug>/, reference with descriptive alt text, replace the placeholder <div> blocks.
• Pattern reference: the Wrike Table / TurboQuote bulk-import docs were done this way (red-box click-target screenshots).