Specify experimental::fundamentals_v1 in the <optional> synopsis, and omit namespace std elsewhere.
Specify experimental::fundamentals_v1 in the <optional> synopsis, and omit namespace std elsewhere.

Even the standard doesn't consistently wrap declarations in a namespace, and
it'll be easier to keep the TS consistent if the header synopsis is a single
point of truth for which namespace a name lives in.

This fixes #5.

jyasskin/html-doc-framework,kwangkim/html-doc-framework,kwangkim/html-doc-framework,cplusplus/html-doc-framework,cplusplus/html-doc-framework