fix a typo in guide/multi-target-exporter.md (#2178)
fix a typo in guide/multi-target-exporter.md (#2178)

Signed-off-by: yngwiewang <7c9c1dc27602b8c834ea42eeec651ed74493cbe1@163.com>

Co-authored-by: yngwiewang <7c9c1dc27602b8c834ea42eeec651ed74493cbe1@163.com>
prometheus/docs,prometheus/docs,prometheus/docs