DOC: Fix typo in blackhole-image.md (#873)

Corrected "studing" to "studying" in the blackhole-image.md file

Author: ChiefMahedi

content/en/case-studies/blackhole-image.md

@@ -22,7 +22,7 @@ Imaging the M87 Black Hole is like trying to see something that is by definition
 
 The [Event Horizon telescope (EHT)](https://eventhorizontelescope.org) is an
 array of eight ground-based radio telescopes forming a computational telescope
-the size of the earth, studing the universe with unprecedented
+the size of the earth, studying the universe with unprecedented
 sensitivity and resolution.  The huge virtual telescope,  which uses a technique
 called very-long-baseline interferometry (VLBI), has an angular resolution of
 [20 micro-arcseconds][resolution] — enough to read a newspaper in New York