remove deprecated option (#102)

Author: jordan-smith721

source/install-from-source.txt

@@ -241,7 +241,6 @@ the project with both ``libbson`` and ``libmongoc``:
 .. code-block:: none
 
    $ cmake -S $SOURCE -B $BUILD \
-      -D ENABLE_EXTRA_ALIGNMENT=OFF \
       -D CMAKE_BUILD_TYPE=RelWithDebInfo \
       -D BUILD_VERSION="$VERSION" \
       -D ENABLE_MONGOC=OFF
@@ -266,11 +265,6 @@ messages and information. Ensure that configuration succeeds before proceeding.
   results. This should be set to the same value as the version of the source
   driver that was downloaded in :ref:`get-src`.
 
-  The ``ENABLE_EXTRA_ALIGNMENT`` argument is part
-  of ``mongo-c-driver`` and corresponds to a deprecated feature that is only
-  enabled by default for ABI compatibility purposes. It is highly recommended to
-  disable this feature whenever possible.
-
   The ``ENABLE_MONGOC=OFF`` argument disabled building ``libmongoc``. We'll build
   that in the next section.