docs: Update documentation for huge pages and balloon

Update docs to reflect that now huge pages can be used alongside the
traditional balloon device. However, note the caveat that memory may not
be reclaimed from the guest.

Signed-off-by: Jack Thomson <[email protected]>

Author: JackThomson2

docs/hugepages.md

@@ -33,15 +33,15 @@ described in our documentation on
 
 ## Known Limitations
 
-Currently, hugetlbfs support is mutually exclusive with the following
-Firecracker features:
-
-- Memory Ballooning via the [Balloon Device](./ballooning.md)
-
-Furthermore, enabling dirty page tracking for hugepage memory negates the
-performance benefits of using huge pages. This is because KVM will
-unconditionally establish guest page tables at 4K granularity if dirty page
-tracking is enabled, even if the host users huge mappings.
+Enabling dirty page tracking for hugepage memory negates the performance
+benefits of using huge pages. This is because KVM will unconditionally establish
+guest page tables at 4K granularity if dirty page tracking is enabled, even if
+the host users huge mappings.
+
+The traditional balloon device reports free pages at 4k granularity, this means
+the device is unable to reclaim the hugepage backing of the guest and drop RSS.
+However, the balloon can still be inflated and used to restrict memory usage in
+the guest.
 
 ## FAQ