Fix Markdown syntax in Annex B document

[Andrew Lilley Brinker]

Currently, the Annex B document includes some minor Markdown errors, including incorrect syntax for triple-backtick-denoted code blocks, where the first line of the code block is on the same line as the triple backticks. This results in GitHub not showing the first line of the block, as it gets interpreted as a language identifier / modifier of the code block rather than as content. The document also includes inconsistent application of single backticks for denoting inline code expressions.