add: space for calculating memory usagee. (#7414)
* add: space for calculating memory usahe.
* Update docs/source/en/using-diffusers/loading.md
Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
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Co-authored-by: Steven Liu <59462357+stevhliu@users.noreply.github.com>
