Check that documentation builds without warnings on nightly

This should ensure that all intra-doc links are correct.

.github/workflows/test.yml

@@ -132,3 +132,18 @@ jobs:
 
       - name: Build static library
         run: cross check --target ${{ matrix.target }}
+
+  check-docs:
+    runs-on: ubuntu-latest
+    name: Check doc links
+    steps:
+      - uses: actions/checkout@v2
+      - name: Install rust nightly
+        uses: actions-rs/toolchain@v1
+        with:
+          toolchain: nightly
+          override: true
+      - name: Check docs build without warnings
+        env:
+          RUSTDOCFLAGS: '-D warnings'
+        run: cargo +nightly doc

src/offset/mod.rs

@@ -403,16 +403,17 @@ pub trait TimeZone: Sized + Clone {
         self.timestamp_opt(secs, nanos as u32).unwrap()
     }
 
-    /// Parses a string with the specified format string and
-    /// returns a `DateTime` with the current offset.
-    /// See the [`format::strftime` module](../format/strftime/index.html)
-    /// on the supported escape sequences.
+    /// Parses a string with the specified format string and returns a
+    /// `DateTime` with the current offset.
     ///
-    /// If the format does not include offsets, the current offset is assumed;
-    /// otherwise the input should have a matching UTC offset.
+    /// See the [`::format::strftime`] module on the
+    /// supported escape sequences.
     ///
-    /// See also `DateTime::parse_from_str` which gives a local `DateTime`
-    /// with parsed `FixedOffset`.
+    /// If the to-be-parsed string includes an offset, it *must* match the
+    /// offset of the TimeZone, otherwise an error will be returned.
+    ///
+    /// See also [`DateTime::parse_from_str`] which gives a [`DateTime`] with
+    /// parsed [`FixedOffset`].
     fn datetime_from_str(&self, s: &str, fmt: &str) -> ParseResult<DateTime<Self>> {
         let mut parsed = Parsed::new();
         parse(&mut parsed, s, StrftimeItems::new(fmt))?;