fix datasource api docs

add double quotes around tags

"Not found" should only be for http path/method not found (404)
if it's about specific resources, we should be explicit for clarity

reflects change in e2f6633d

Removed some editor srv properites from data sources, they are not needed there anymore, they are in plugin.json, Closes #2283

Work arround for slower template variable dropdown when variable has many thousand values, now only top 1000 values are rendered to html, you can still search all values, Closes #2246

Fix 'paranthesis' typo to 'parenthesis'

Allow pipe ('|') in Graphite lexer

This typo is most noticable in the Graphite lexer error hint message.

Allow for Graphite lexer to understand metric names like
'net|usage_average'.

fix config flag

Support dot (.) in metric name

I'd like to update the regex in order to support dot in metric name. For example "cpu.usage.average".