docs/develop/porting.rst: Fix build and import problems in the example.

docs/develop/porting.rst

@@ -146,6 +146,9 @@ The following is an example of an ``mpconfigport.h`` file:
    #define MICROPY_ERROR_REPORTING                 (MICROPY_ERROR_REPORTING_TERSE)
    #define MICROPY_FLOAT_IMPL                      (MICROPY_FLOAT_IMPL_FLOAT)
 
+   // Enable u-modules to be imported with their standard name, like sys.
+   #define MICROPY_MODULE_WEAK_LINKS               (1)
+
    // Fine control over Python builtins, classes, modules, etc.
    #define MICROPY_PY_ASYNC_AWAIT                  (0)
    #define MICROPY_PY_BUILTINS_SET                 (0)
@@ -296,7 +299,7 @@ like this:
        mphalport.c \
        ...
 
-   SRC_QSTR += modport.c
+   SRC_QSTR += modmyport.c
 
 If all went correctly then, after rebuilding, you should be able to import the new module: