Tidy releases of all AS-11 Specs

[thomasheritage]

• [x] For all AS-11 Specs, revert release titles (so that the Specification level terms used match those in the Specification included in the bundled release)
• [ ] For all AS-11 Specs, create a new release (+ 0.0.1) if the Specification level terms used in the previous release are out-of-date. Include a small changelog of major changes (probably not much except these Specification level changes, but check)

[thomasheritage]

DO this after other issues e.g. #137

[Matthew-Marks]

Specs that need point releases due to having latest release before 20180718 when the Spec Level terms were changed:

• [x] UK_DPP_SD (Specification -> Specification (Stable))
• [x] UK_DPP_HD (Specification -> Specification (Stable))
• [x] X2 (Proposed Specification -> Specification)
• [x] X7 (Proposed Specification -> Specification)
• [x] X9 (Proposed Specification -> Specification)