arm64/booting: Add missing colon to FA64 entry

The booting documentation for FEAT_SME_FA64 is missing a colon that is
normally present, add it.
Signed-off-by: NMark Brown <broonie@kernel.org>
Link: https://lore.kernel.org/r/20221107171913.294565-1-broonie@kernel.orgSigned-off-by: NWill Deacon <will@kernel.org>

Documentation/arm64/booting.rst

@@ -348,7 +348,7 @@ Before jumping into the kernel, the following conditions must be met:
 
     - HWFGWTR_EL2.nSMPRI_EL1 (bit 54) must be initialised to 0b01.
 
-  For CPUs with the Scalable Matrix Extension FA64 feature (FEAT_SME_FA64)
+  For CPUs with the Scalable Matrix Extension FA64 feature (FEAT_SME_FA64):
 
   - If EL3 is present: