Update README.md

Tool > Locking is very specific and not general enough. Guidelines are fairly specific to MD/OP type sections, but if followed in SYC/M&M could cause problems.  Eg. Wouldn't want to lock old versions in M&M or SYC. SYC we lock things like Terraria videos and redirect so that others know of Terraria forums.
Also repeated suggestions are redundant topics, so might as well remove that.
Maybe it's worth adding more specific guides to sectional moderation sections.