Update intro and URLs

Author: thomas-zahner

README.md

@@ -1,12 +1,13 @@
-A collection of ideas, programs and scripts to make [lychee](https://github.com/lycheeverse/lychee/) compatible with additional file formats.
+A collection of use-cases and scripts to make [lychee] compatible with additional file formats.
 
 Out of the box lychee supports HTML, Markdown and plain text formats.
-More precisely, HTML files are parsed as HTML5 with the use of the [html5ever](https://github.com/servo/html5ever) parser
-and Markdown files are treated as [CommonMark](https://commonmark.org/) with the use of [pulldown-cmark](https://github.com/pulldown-cmark/pulldown-cmark/).
+More precisely, HTML files are parsed as HTML5 with the use of the [html5ever] parser.
+Markdown files are treated as [CommonMark] with the use of [pulldown-cmark].
 
 For any other file format lychee falls back to a "plain text" mode.
-This means that [linkify](https://github.com/robinst/linkify) attempts to extract URLs on a best-effort basis.
-If invalid UTF-8 characters are encountered the input file is skipped.
+This means that [linkify] attempts to extract URLs on a best-effort basis.
+If invalid UTF-8 characters are encountered, the input file is skipped.
+This is because it is assumed that the file is in a binary format lychee cannot understand.
 
 # Preprocess files
 
@@ -20,7 +21,7 @@ as no parameters can be supplied from the CLI directly.
 lychee files/* --preprocess ./preprocess.sh
 ```
 
-Take a look at [preprocess.sh](./preprocess.sh) to see how this is done.
+Take a look at [preprocess.sh] to see how this is done.
 
 # Converting file formats
 
@@ -34,7 +35,7 @@ pandoc "$1" --to=html --wrap=none --markdown-headings=atx
 
 ## odp, pptx, ods, xlsx
 
-LibreOffice can convert documents to various formats.
+[LibreOffice] can convert documents to various formats.
 Unfortunately, it does not support printing the result to stdout directly as of 2025,
 as the `--cat` option is not compatible with `--convert-to`.
 This makes usage a bit clumsy.
@@ -50,7 +51,7 @@ rm "$file"
 
 ## AsciiDoc
 
-Using [asciidoctor](https://docs.asciidoctor.org/) we can convert AsciiDoc to HTML.
+Using [asciidoctor] we can convert AsciiDoc to HTML.
 This ensures that URLs are properly interpreted.
 
 ```bash
@@ -59,7 +60,7 @@ asciidoctor -a stylesheet! "$1" -o -
 
 ## PDF
 
-Using poppler-utils we can convert PDFs to HTML:
+Using [poppler-utils] we can convert PDFs to HTML:
 
 ```bash
 pdftohtml -i -s -stdout "$1"
@@ -68,7 +69,7 @@ pdftohtml -i -s -stdout "$1"
 pdftotext "$1" -
 ```
 
-Alternatively, pdftk can be used to extract URI directives from PDFs.
+Alternatively, [pdftk] can be used to extract URI directives from PDFs.
 Source: https://unix.stackexchange.com/a/531883
 
 ```bash
@@ -90,10 +91,22 @@ Because of that, it's the user's responsibility to transform CSV into a format l
 
 ### csvtk
 
-[csvtk](https://github.com/shenwei356/csvtk) is a toolkit to work with CSV data.
+[csvtk] is a toolkit to work with CSV data.
 Apart from many advanced features, it allows us to convert and pretty-print CSV.
 One possible way to transform the data is:
 
 ```bash
 csvtk csv2json "$1"
 ```
+
+[lychee]: https://github.com/lycheeverse/lychee/
+[linkify]: https://github.com/robinst/linkify
+[html5ever]: https://github.com/servo/html5ever
+[CommonMark]: https://commonmark.org/
+[pulldown-cmark]: https://github.com/pulldown-cmark/pulldown-cmark/
+[preprocess.sh]: ./preprocess.sh
+[asciidoctor]: https://docs.asciidoctor.org/
+[csvtk]: https://github.com/shenwei356/csvtk
+[LibreOffice]: https://help.libreoffice.org/latest/he/text/shared/guide/start_parameters.html
+[poppler-utils]: https://poppler.freedesktop.org/
+[pdftk]: https://gitlab.com/pdftk-java/pdftk