doc/PKGBUILD: document libdeps

Signed-off-by: Florian Pritz <bluewind@xinu.at>

doc/PKGBUILD.5.txt

@@ -150,6 +150,11 @@ name. The syntax is: `source=('filename::url')`.
 	form 'name<>version', where <> is one of five comparisons: >= (greater
 	than or equal to), <= (less than or equal to), = (equal to), > (greater
 	than), or < (less than).
++
+If the dependency name appears to be a library (ends with .so), makepkg will
+try to find a binary that depends on the library in the built package and
+append the version needed by the binary. Appending the version yourself
+disables auto detection.
 
 *makedepends (array)*::
 	An array of packages that this package depends on to build, but are not
@@ -186,6 +191,10 @@ name. The syntax is: `source=('filename::url')`.
 	dependency of other packages. Provisions involving the '>' and '<'
 	operators are invalid as only specific versions of a package may be
 	provided.
++
+If the provision name appears to be a library (ends with .so), makepkg will
+try to find the library in the built package and append the correct
+version. Appending the version yourself disables auto detection.
 
 *replaces (array)*::
 	An array of packages that this package should replace, and can be used