Typo fix: Usally -> Usually.
Typo fix: Usally -> Usually.

PR:		docs/34918
Submitted by:	Harry Newton <harry_newton@telinco.co.uk>

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase