link exec_group starlark api docs and remove TODO
@@ -30,17 +30,16 @@ like linking in c++ builds without over-allocating to less demanding tasks.
## Defining execution groups
-During rule definition, rule authors can declare a set of execution groups. On
-each execution group, the rule author can specify everything needed to select
-an execution platform for that execution group, namely any constraints via
-`exec_compatible_with` and toolchain types via `toolchain`. If an execution group
-is created as empty (no specified toolchains or constraints) it will
-automatically inherit these
+During rule definition, rule authors can
+[declare](https://docs.bazel.build/versions/master/skylark/lib/globals.html#exec_group)
+a set of execution groups. On each execution group, the rule author can specify
+everything needed to select an execution platform for that execution group,
+namely any constraints via `exec_compatible_with` and toolchain types via
+`toolchain`. If an execution group is created as empty (no specified toolchains
+or constraints) it will automatically inherit these
[parameters](https://docs.bazel.build/versions/master/skylark/lib/globals.html#rule)
from the rule to which the group is attached.
-TODO(juliexxia): link to exec_group method docs when they get released in bazel.
-
```python
# foo.bzl
my_rule = rule(
