Clarify unknown license keys #2827

Update the notes for license data files with `unknown` license
keys with text authored by @DennisClark. See also:
#3021

Reference: #2827
Signed-off-by: Ayan Sinha Mahapatra <ayansmahapatra@gmail.com>

Author: AyanSinhaMahapatra

src/licensedcode/data/licenses/free-unknown.yml

@@ -5,4 +5,5 @@ category: Unstated License
 owner: Unspecified
 is_unknown: yes
 spdx_license_key: LicenseRef-scancode-free-unknown
-
+notes: This case appolies to software with a notice that refers in a non-specific manner to a
+  free or open-source license, but where it is not possible to determine that specific license.

src/licensedcode/data/licenses/unknown-license-reference.yml

@@ -4,6 +4,8 @@ name: Unknown License file reference
 category: Unstated License
 owner: Unspecified
 is_unknown: yes
-notes: This is reference to a license file with no clear license. this was known before as "see-license"
-    and "license-file-reference"
 spdx_license_key: LicenseRef-scancode-unknown-license-reference
+notes: This applies to the case of a file with no clear license, which may be referenced
+    via URL or text such as "See license in..." or "This file is licensed under...",
+    but where the reference cannot be resolved to a specific named, public license.
+    This was known before as "see-license" and "license-file-reference"

src/licensedcode/data/licenses/unknown-spdx.yml

@@ -5,5 +5,4 @@ category: Unstated License
 owner: Unspecified
 is_unknown: yes
 spdx_license_key: LicenseRef-scancode-unknown-spdx
-notes: This is something that clearly ressembles a license in an SPDX license
- expression but is not conclusively an SPDX license ID.
+notes: This applies to an invalid reference to an SPDX license identifier.

src/licensedcode/data/licenses/unknown.yml

@@ -5,4 +5,5 @@ category: Unstated License
 owner: Unspecified
 is_unknown: yes
 spdx_license_key: LicenseRef-scancode-unknown
-notes: This is something that clearly ressembles a license but is not conclusive.
+notes: This applies to the case where there is text referring to a license, but it is not
+  possible to determine exactly which license.