Explain why the apt module does not do implicit regex matches on package name since this is different than the apt-get command line tool.

Fixes #1258

lib/ansible/modules/packaging/os/apt.py

@@ -29,7 +29,7 @@ version_added: "0.0.2"
 options:
   name:
     description:
-      - A package name, like C(foo), or package specifier with version, like C(foo=1.0). Name wildcards (fnmatch) like C(apt*) and version wildcards like C(foo=1.0*) are also supported.
+      - A package name, like C(foo), or package specifier with version, like C(foo=1.0). Name wildcards (fnmatch) like C(apt*) and version wildcards like C(foo=1.0*) are also supported.  Note that the apt-get commandline supports implicit regex matches here but we do not because it can let typos through easier (If you typo C(foo) as C(fo) apt-get would install packages that have "fo" in their name with a warning and a prompt for the user.  Since we don't have warnings and prompts before installing we disallow this.  Use an explicit fnmatch pattern if you want wildcarding)
     required: false
     default: null
   state:
@@ -271,6 +271,14 @@ def expand_dpkg_options(dpkg_options_compressed):
     return dpkg_options.strip()
 
 def expand_pkgspec_from_fnmatches(m, pkgspec, cache):
+    # Note: apt-get does implicit regex matching when an exact package name
+    # match is not found.  Something like this:
+    # matches = [pkg.name for pkg in cache if re.match(pkgspec, pkg.name)]
+    # (Should also deal with the ':' for multiarch like the fnmatch code below)
+    #
+    # We have decided not to do similar implicit regex matching but might take
+    # a PR to add some sort of explicit regex matching:
+    # https://github.com/ansible/ansible-modules-core/issues/1258
     new_pkgspec = []
     for pkgspec_pattern in pkgspec:
         pkgname_pattern, version = package_split(pkgspec_pattern)