[docs] Remove hyphen-underscore statement in package() migration doc

After fxrev.dev/458394, the package rules do not enforce
hyphens or dashes in package names.

The package() migration doc has been updated to reflect this.

Change-Id: I2cbe355aabcea7262002f19de2605a874f083d29
Reviewed-on: https://fuchsia-review.googlesource.com/c/fuchsia/+/475940
Reviewed-by: Shai Barack <shayba@google.com>
Commit-Queue: Xyan Bhatnagar <xbhatnag@google.com>
diff --git a/docs/development/components/build.md b/docs/development/components/build.md
index 685db0c..b4d06d313 100644
--- a/docs/development/components/build.md
+++ b/docs/development/components/build.md
@@ -1237,9 +1237,6 @@
 
 *   Targets that generate executables or data files are not expected to change
     in a migration.
-*   Names for packages are expected to have dashes ("-") instead of underscores
-    ("_"). The same is not required for components, though it's recommended for
-    consistency.
 *   Previously, `meta/service.cmx` was given the destination `"timekeeper.cmx"`
     which placed it in `meta/timekeeper.cmx`. With `fuchsia_component()`, the
     given manifest is automatically renamed per the component name