Give each template its own README

The root README keeps what is shared — dependencies, accessibility, the
scripts — and links to a per-template README for how to build and what is
in it. The Posters section moves to poster_template/README.md with a
pointer left behind, since it is that template's caveat.

slides_template/README.md replaces the two READMEs that came with
beamer-mako.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

slides_template/README.md

@@ -0,0 +1,80 @@
+# Slides Template
+
+Presentation slides on the [ltx-talk](https://github.com/josephwright/ltx-talk)
+class, which was written with tagging as a design goal. See the
+[root README](../README.md) for what tagging buys and how to check it.
+
+## Requirements
+
+* LuaLaTeX
+* ltx-talk, from `texlive-latex-recommended`. It needs LaTeX 2025-11-01 or
+  later, which is newer than TeX Live 2025 as first released; Overleaf's
+  TeX Live 2025 may predate it, so compile there before relying on it.
+* `python3-pypdf`, for assembling the notes PDF
+
+```
+apt install latexmk texlive-luatex texlive-latex-recommended \
+  texlive-fonts-extra python3-pypdf
+```
+
+Slides are set in Open Sans and Roboto Mono, both from `texlive-fonts-extra`.
+
+## Building
+
+```
+make slides      # the deck
+make notes       # double-width slide and notes pages, for presenting
+make pdfpc       # build the notes PDF and open it in pdfpc
+```
+
+Share the slides build. The notes build is not tagged and exists to be looked
+at while talking.
+
+## Writing slides
+
+Give frame titles as `\frametitle`, not as the braced argument to `frame`. The
+class treats `\begin{frame}{Title}` as body text, so a title given that way is
+not tagged as a heading.
+
+Coming from beamer:
+
+| beamer | here |
+|---|---|
+| `\begin{frame}{Title}` | `\frametitle{Title}` inside the frame |
+| `\begin{frame}[standout]{}` | `\standout{...}` |
+| `\sectionpage` from the theme | `\section{...}` then `\sectionpage` |
+| `\subsectionpage` | `\subsection{...}` then `\subsectionpage` |
+| `\note{...}`, `\note[item]{...}` | same, after `\usepackage{talk-notes}` |
+| `\appendix` | same |
+| `\alert{...}`, `\item<2->`, `\pause` | same |
+| `\only<1>{...}` | avoid; use `\pause` or `\begin{itemize}[<+->]` |
+
+## Speaker notes
+
+ltx-talk has no `\note` command (see
+[issue #156](https://github.com/josephwright/ltx-talk/issues/156)).
+`talk-notes.sty` defines one that records its text to a side file and
+contributes nothing to the slides; `mknotes` reads that file afterwards and
+builds the presenter PDF.
+
+Write notes with `\note{...}`, or `\note<2->{...}` to bind one to particular
+slides of a frame. As in beamer, plain notes run together as text, each
+starting a new paragraph, and `\note[item]{...}` adds an entry to a numbered
+list printed after them.
+
+`make notes` writes `<jobname>-notes.pdf`, the double-width version you present
+from. Show it with [dspdfviewer](https://github.com/dannyedel/dspdfviewer),
+[pdfpc](https://pdfpc.github.io/), or the web viewers
+[Beamer Viewer](https://beamerviewer.euxane.eu/) and
+[backstage](https://bckstg.xyz/).
+
+To use notes in another ltx-talk document, copy `mknotes` and `talk-notes.sty`
+across and load the package. `mknotes` picks up `fonts.tex` when it is present,
+so the notes match the deck; `--preamble FILE` names a different fragment.
+
+## Theme
+
+`trantor.sty` is [Marco Pompili's](https://github.com/mrc-pop)
+[Metropolis-like theme](https://github.com/mrc-pop/trantor) for ltx-talk,
+vendored with a licence header added and the font block left to the document.
+Re-vendor from the fork rather than editing this copy.