Fix typo in cluster_advanced.rst (Lightning-AI#13173)

Author: jxmorris12

docs/source/clouds/cluster_advanced.rst

@@ -7,7 +7,7 @@ Run on an on-prem cluster (advanced)
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-Run on a SLRUM managed cluster
+Run on a SLURM managed cluster
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 Lightning automates the details behind training on a SLURM-powered cluster. In contrast to the general purpose
 cluster above, the user does not start the jobs manually on each node and instead submits it to SLURM which