Remove unused docker files

linkchecker/Dockerfile

-FROM debian:buster
-
-###############
-# Linkchecker #
-###############
-
-RUN apt update && apt install -y linkchecker
-
-WORKDIR /src/linkchecker
-
-ENTRYPOINT ["/usr/bin/linkchecker"]
-
-CMD ["--help"]
-

linter/Dockerfile

-FROM webpage:base
-
-##########
-# Linter #
-##########
-
-RUN apt update && apt install -y nodejs npm
-
-RUN npm install -g markdownlint-cli
-
-WORKDIR /src/linter
-
-ENTRYPOINT ["/usr/local/bin/markdownlint"]
-
-CMD ["--help"]
-

linter/config.json

-{
-    "default": false,
-    "first-heading-h1": true,
-    "header-increment": true,
-    "heading-style": { "style": "atx" },
-    "no-missing-space-atx": true,
-    "no-multiple-space-atx": true,
-    "blanks-around-headings": true,
-    "no-emphasis-as-heading": true,
-    "first-line-heading": true,
-    "single-title": true,
-    "no-empty-links": true,
-    "no-alt-text": true,
-    "no-multiple-blanks": true,
-    "single-trailing-newline": true,
-    "blanks-around-fences": true,
-    "blanks-around-lists": true,
-    "commands-show-output": true,
-    "line-length": { "line_length": 100, "code_blocks": false, "tables": false}
-}