Improve liblockdep documentation a little

Add long descriptions for all liblockdep packages, and a README.Debian
for liblockdep-dev which links to some articles about it.

debian/liblockdep-dev.README.Debian

@@ -0,0 +1,13 @@
+liblockdep for Debian
+---------------------
+
+liblockdep does not have proper documentation, but these articles
+provide an introduction:
+
+    https://lwn.net/Articles/536363/
+    http://www.vctlabs.com/posts/2014/Jul/09/liblockdep/
+
+'lockdep-design.txt' explains some more detail about what lockdep
+does, both in the kernel and as liblockdep.
+
+ -- Ben Hutchings <ben@decadent.org.uk>, Fri, 14 Aug 2015 14:22:55 +0200

debian/templates/control.main.in

@@ -78,7 +78,8 @@ Recommends: liblockdep-dev
 Section: devel
 Multi-Arch: allowed
 Description: Runtime locking correctness validator
- TBD
+ lockdep is a wrapper for programs that use the pthreads API, which detects
+ actual and potential deadlocks and other locking bugs.
 
 Package: liblockdep@version@
 Architecture: linux-any
@@ -86,7 +87,8 @@ Depends: ${shlibs:Depends}, ${misc:Depends}
 Section: libs
 Multi-Arch: same
 Description: Runtime locking correctness validator - shared library
- TBD
+ liblockdep is a library for programs that use the pthreads API, which can
+ be used to detect actual and potential deadlocks and other locking bugs.
 
 Package: liblockdep-dev
 Architecture: linux-any
@@ -94,4 +96,5 @@ Depends: ${shlibs:Depends}, ${misc:Depends}
 Section: libdevel
 Multi-Arch: same
 Description: Runtime locking correctness validator - development files
- TBD
+ liblockdep is a library for programs that use the pthreads API, which can
+ be used to detect actual and potential deadlocks and other locking bugs.