sqlite: Update docs

Change-Id: I82c593c48c33259e561fc03e0ff0657aadebdde3
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2021007
Auto-Submit: Darwin Huang <huangdarwin@chromium.org>
Reviewed-by: Chris Mumford <cmumford@google.com>
Commit-Queue: Darwin Huang <huangdarwin@chromium.org>
Cr-Commit-Position: refs/heads/master@{#735156}

third_party/sqlite/README.chromium

@@ -162,11 +162,12 @@ cd third_party/sqlite
 export OLD=3300100
 export NEW=3310000
 export GNU_SED=sed  # OSX: "brew install gnu-sed", then use "gsed" here.
+export YEAR=2020
 
 #### Download and unpack the new SQLite release.
 git new-branch sqlite-new-upstream
 # URL from "Alternative Source Code Formats" at https://sqlite.org/download.html
-curl https://sqlite.org/2019/sqlite-src-${NEW}.zip > upstream.zip
+curl https://sqlite.org/${YEAR}/sqlite-src-${NEW}.zip > upstream.zip
 mkdir sqlite-src-${NEW}
 unzip ./upstream.zip -d sqlite-src-${NEW}
 rm ./upstream.zip
@@ -276,9 +277,10 @@ git rm -r sqlite-src-${OLD}
 git commit -m "sqlite: Remove source code for old release ${OLD}."
 git cl upload
 
-Note that things can be broken down differently, if you prefer.  For instance,
-adding the new version of the SQLite distro and removing the old one can be
-distinct CLs.
+### Update README.chromium to reference the new sqlite version number.
+# Update:
+#  (1) the header's "Version"
+#  (2) `export OLD` and `export NEW` values.
 
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