Help: Prevent .so from being treated as a roff macro

Move `.so` to the line above - otherwise it is being treated as a `roff`
macro, i.e.:

    $ mandoc -Tlint /usr/local/man/man7/cmake-properties.7 | head -n 3
    mandoc: /usr/local/man/man7/cmake-properties.7:1131:2: WARNING: .so is fragile, better use ln(1): so libraries.
    mandoc: /usr/local/man/man7/cmake-properties.7: ERROR: No such file or directory
    mandoc: /usr/local/man/man7/cmake-properties.7:1131:15: ERROR: .so request failed: .so libraries.

and causes other issues down the line.

Help/prop_tgt/ANDROID_NATIVE_LIB_DIRECTORIES.rst

@@ -1,8 +1,8 @@
 ANDROID_NATIVE_LIB_DIRECTORIES
 ------------------------------
 
-Set the Android property that specifies directories to search for the
-.so libraries.
+Set the Android property that specifies directories to search for the ``.so``
+libraries.
 
 This a string property that contains the directory paths separated
 by semicolons.