started document on linguistic structures in the resource

doc/resource.txt

@@ -0,0 +1,31 @@
+The GF Resource Grammar Library
+
+The outermost linguistic structure is Text. Texts are composed
+from Phrases followed by punctuation marks - either of ".", "?" or
+"!! (with their proper variants in Spanish and Arabic). Here is an 
+example of a text.
+
+  John walks. Why? He doesn't want to sleep!
+
+Phrases are mostly built from Utterances, which in turn are
+declarative sentences, questions, or imperatives - but there
+are also "one-word utterances" consisting of noun phrases
+or other subsentential phrases. Some Phrases are more primitive,
+for instance "yes" and "no". Here are some examples of Phrases.
+
+  yes
+  come on, John
+  but John walks
+  give me the stick please
+  don't you know that he is sleeping
+  a glass of wine
+  a glass of wine please
+
+There is no connection between the punctuation marks and the
+types of utterances. This reflects the fact that the punctuation
+mark in a real text is selected as a function of the speech act
+rather than the grammatical form of an utterance. The following
+text is thus well-formed.
+
+  John walks. John walks? John walks!
+

lib/resource-1.0/abstract/Common.gf

@@ -20,13 +20,16 @@ abstract Common = {
 -- Constructed in [Text Text.html]: $Text$.
 
     Text ;  -- text consisting of several phrases  e.g. "He is here. Why?"
-    Phr ;   -- phrase in a text                    e.g. "But get out please."
 
--- Constructed in [Phrase Phrase.html]: $Phr$ and
+-- Constructed in [Phrase Phrase.html]:
 
+    Phr ;   -- phrase in a text                    e.g. "but be quiet please"
     Utt ;   -- sentence, question, word...         e.g. "be quiet"
     Voc ;   -- vocative or "please"                e.g. "my darling"
     PConj ; -- phrase-beginning conj.              e.g. "therefore"
+
+-- Constructed in [Sentence Sentence.html]:
+
     SC ;    -- embedded sentence or question       e.g. "that it rains"
 
 --2 Adverbs