update docs

.doc/doki/doc/image-requirements.md

@@ -37,3 +37,20 @@ npm install -g @mermaid-js/mermaid-cli
 ```
 
 If `mmdc` is not found, Mermaid blocks are displayed as plain code blocks.
+
+## Graphviz diagrams
+
+Rendering fenced code blocks tagged `` ```dot `` or `` ```graphviz `` requires [`dot`](https://graphviz.org/) (from the Graphviz suite) to be installed and available in `PATH`.
+
+```
+# macOS
+brew install graphviz
+
+# Debian / Ubuntu
+sudo apt install graphviz
+
+# Fedora
+sudo dnf install graphviz
+```
+
+If `dot` is not found, Graphviz blocks are displayed as plain code blocks.

.doc/doki/doc/markdown-viewer.md

@@ -27,6 +27,18 @@ tiki github.com/boolean-maybe/tiki
 
 press `q` to quit
 
+## Open image files
+
+Likewise, you can open image files:
+```
+tiki my-file.png
+```
+or 
+
+```
+tiki https://bellard.org/bpg/2.png
+```
+
 ## Navigate links
 
 with a Markdown file open press `Tab/Shift-Tab` to select next/previous link in the file

README.md

@@ -25,7 +25,7 @@ documentation, brainstorming ideas, incomplete implementations, AI prompts and p
 Stick them in your repo. Keep around for as long as you need. Find them back in **git** history. Make issues out of them
 and take them through an agile lifecycle. `tiki` helps you save and organize these files:
 
-- Standalone **Markdown viewer** - view and edit Markdown files, navigate to local/external/GitHub/GitLab links, image display
+- Standalone **Markdown viewer** - view and edit Markdown or image files, navigate to local/external/GitHub/GitLab links, image display
 - Keep, search, view and version Markdown files in the **git repo**
 - **Wiki-style** documentation with multiple entry points
 - Keep a **to-do list** with priorities, status, assignee and size