docs: Use common conventions for shared libs

Use common conventions for documentation of shared library version and
soversion. In general, the numeric version part is expected to be first
component of version, so suggest this in the example code.

docs/markdown/Build-targets.md

@@ -36,7 +36,7 @@ ignored if the library is configured as static at the compile time.
 
 ```meson
 project('shared lib', 'c')
-library('mylib', 'source.c', version : '1.2.3', soversion : '0')
+library('mylib', 'source.c', version : '1.2.3', soversion : '1')
 ```
 
 It is common to build a library and then an executable that links