Changes

bibliography.adoc: add TW-TS-* references

Some Osmocom components include support for interfaces that are
defined in Themyscira Wireless specs (TW-TS):

* OsmoBTS includes support for TW-TS-001, may also support TW-TS-002
  for HRv1 codec in the future;
* OsmoBSC includes support for TW-TS-003 BSSMAP extension;
* TW-TS-005 hex file format can be used in some unit tests.

Therefore, these specs should be linked from Osmocom bibliography.

Change-Id: Ia34a61b5f834f2c70f81012dcc816dd6014c784f