Create lint to detect placeholder text

[SamWilsn]

Please don't include placeholder text. TBD is appropriate if you don't have any content yet.

cc @SamWilsn we should create a lint rule for people who leave the placeholder text in.

Originally posted by @MicahZoltu in ethereum/EIPs#5300 (comment)

[SamWilsn]

One way to implement this would be to lint for TBD|TODO and put that at the start of each section's placeholder text.

[MicahZoltu]

What would the advantage of this strategy be vs just doing a string match against the placeholder text itself?

[SamWilsn]

People re-wrap the text all the time, so doing a string match on something long might not always catch it. I guess I could do a whitespace agnostic search too.

A lint to detect TDB and TODO in Review might be useful though.