Clarify limited logo usage rights granted by orgs (pantsbuild#16384)

Several users have reported that securing internal permission to put their company logo on Who Uses Pants is easiest when legal/PR/etc have clarity that the usage rights granted are limited. This is an attempt to communicate more clearly with people interacting with this form and those whose authorization they seek.

.github/ISSUE_TEMPLATE/user_registration.yml

@@ -33,8 +33,10 @@ body:
       description: |
         We'd love to use your company's logo on the Users Page!
 
-        Please ensure that you have the right to grant us permission to use the logo in
-        this manner before adding it.
+        By attaching it here, permission is granted to display this logo on pantsbuild.org 
+        in affirmation that the organization uses Pants. No other usage rights are granted to 
+        the organization's intellectual property. Please ensure that you have the right to 
+        grant us permission to use the logo in this manner before adding it. 
 
         If you're unsure, please submit this page without the logo, and we can revisit it later,
         if/when permission has been established. The other information is still very helpful!