[analyzer] Fix a typo in `RegionStore.txt`.

[MTC]

Summary

The typo of the description for default bindings can be confusing.

[NoQ]

Yay somebody reads those.

docs/analyzer/RegionStore.txt

 this value is used as the value of the original region. The search ends when
 the base region is reached, at which point the RegionStore will pick an
 appropriate default value for the region (usually a symbolic value, but
 sometimes zero, for static data, or "uninitialized", for stack variables).
 
   int manyInts[10];
   manyInts[1] = 42;   // Creates a Direct binding for manyInts[1].
   print(manyInts[1]); // Retrieves the Direct binding for manyInts[1];
-  print(manyInts[0]); // There is no Direct binding for manyInts[1].
+  print(manyInts[0]); // There is no Direct binding for manyInts[0].
                       // Is there a Default binding for the entire array?
                       // There is not, but it is a stack variable, so we use
                       // "uninitialized" as the default value (and emit a
                       // diagnostic!).
 
 NOTE: The fact that bindings are stored as a base region plus an offset limits
 the Default Binding strategy, because in C aggregates can contain other
 aggregates. In the current implementation of RegionStore, there is no way to
Here's a concrete example:
     CGPoint p;
     p.x = 42;       // A Direct binding is made to the FieldRegion 'p.x'.
     CGPoint p2 = p; // A LazyCompoundVal is created for 'p', along with a
                     // snapshot of the current store state. This value is then
                     // used as a Default binding for the VarRegion 'p2'.
     return p2.x;    // The binding for FieldRegion 'p2.x' is requested.
                     // There is no Direct binding, so we look for a Default
                     // binding to 'p2' and find the LCV.
-                    // Because it's an LCV, we look at our requested region
+                    // Because it's a LCV, we look at our requested region
                     // and see that it's the '.x' field. We ask for the value
                     // of 'p.x' within the snapshot, and get back 42.