Add comment regarding mapping of instrumentations

opentelemetry-instrumentation/src/opentelemetry/instrumentation/bootstrap.py

@@ -23,7 +23,14 @@
 logger = getLogger(__file__)
 
 
-# target library to desired instrumentor path/versioned package name
+# A mapping of "target library" to "desired instrumentor path/versioned package
+# name". Used as part of the `opentelemetry-bootstrap` command which looks at
+# libraries used by the application that is to be instrumented, and handles
+# automatically installing the appropriate instrumentations for that app.
+# This helps for those who prefer to turn on as much instrumentation as
+# possible, and don't want to go through the manual process of combing through
+# the libraries their application uses to figure which one can be
+# instrumented.
 instrumentations = {
     "aiohttp-client": "opentelemetry-instrumentation-aiohttp-client>=0.15b0",
     "aiopg": "opentelemetry-instrumentation-aiopg>=0.15b0",