README.md: Use <> around all hyperlinks to render them as links in cgit
README.md: Use <> around all hyperlinks to render them as links in cgit

Change-Id: I4b1004d5275972249d463083e0c2af41dc46dad2

osmocom/libosmo-abis,osmocom/libosmo-abis,osmocom/libosmo-abis