Improve organization of processor docs

[dedemorton]

The documentation about processors needs a little restructuring. There's some redundant info in the container topic and the topic about defining processors. Mixing the discussion about including/excluding lines with the content about processors might be confusing to new users. The focus of this section should be on processors with maybe a note that points of to docs that describe how to include and exclude lines.

[dedemorton]

Closing because we will not be making these changes to the Beats documentation