add vale code formatting checks

.github/vale/Docker/CodeIndentation.yml

@@ -0,0 +1,9 @@
+extends: existence
+message: "Indent nested code blocks by 3 spaces and double-nested code blocks by 5 spaces."
+link: https://docs.docker.com/contribute/style/formatting/#best-practice-for-commands
+level: warning
+scope: raw
+# check for 1, 2, 4, 6 or more spaces at start of line before code fence (```)
+#If not indented by 3 spaces at first level or 5 spaces at second level, then a hidden space is inserted and copied by the copy code feature.
+raw:
+  - '(?m:^[ ]{4}\`\`\`|^[ ]{6,}\`\`\`|^[ ]{1}\`\`\`|^[ ]{2}\`\`\`)'

.github/vale/Docker/CodeOutput.yml

@@ -0,0 +1,8 @@
+extends: existence
+message: "If you expect users to copy and run the command, specify output in a separate code block."
+link: https://docs.docker.com/contribute/style/formatting/#best-practice-for-commands
+level: warning
+scope: raw
+#check for console code fence followed by one line with $ or #, and not ending in `or \. Followed by more lines without $ or # and terminated by code fence
+raw:
+  - '(?m:\`\`\`console\n+(\s*.*(\$|#).*[^\`\\]$)([^\$#(\`\`\`)]+\n)\s*\`\`\`)'

.github/vale/Docker/CodeSingleCommand.yml

@@ -0,0 +1,8 @@
+extends: existence
+message: "If you expect users to copy and run the command, specify one command per code block."
+link: https://docs.docker.com/contribute/style/formatting/#best-practice-for-commands
+level: warning
+scope: raw
+#check for console code fence followed by two or more newlines with $ or #
+raw:
+  - '(?m:\`\`\`console\n+(\s*.*(\$|#).*\n){2,})'