Fix A5 description concerning A5/2 (not in use).
Fix UICC: 'Circuit Card', not 'Chip Circuit', and replace 'FIXME'.
NITB: like OsmoNITB just without Osmo, reference OsmoNITB.
Add some words/explanations (FPGA, MSC, OXCO, UICC, VTY).
Fix minor typos ('Freee', 'usees', over-eager dashes '-',
capitalisation).
Use 'an' before acronyms pronounced starting with a vocal ('S', 'M').
Use 'a' before 'U'.
Unify style:
Use semicoli ';' instead of periods '.' or commas ',' where appropriate.
Use lower case letters after semicoli.
The manuals existed in different form for several years in an internal
sysmocom repository. However, since they had just recently been
converted from docboox-xml to asciidoc and all files have been
re-shuffled for enabling the public release, there's not much point in
keeping the history with git-filter-branch.