Fix various issues with Markdown docs

docs/useful_urls.md

 # Useful URLs
 
 Chromium has a lot of different pages for a lot of different things.
 This page aims to be a repository of useful links that people may find useful.
 
 ## Build Status
 
+|:---------------------------------------------|:------------------------|
 | http://build.chromium.org/p/chromium/console | Main buildbot waterfall |
-|:---------------------------------------------|:------------------------|
 | http://chromium-status.appspot.com/lkgr      | Last Known Good Revision. Trybots pull this revision from trunk. |
 | http://chromium-status.appspot.com/revisions | List of the last 100 potential LKGRs |
 | http://build.chromium.org/p/chromium/lkgr-status/ | Status dashboard for LKGR |
 | http://build.chromium.org/p/tryserver.chromium/waterfall?committer=developer@chromium.org | Trybot runs, by developer |
 | http://chromium-status.appspot.com/status_viewer | Tree uptime stats       |
 | http://chromium-cq-status.appspot.com        | Commit queue status     |
 | http://codereview.chromium.org/search?closed=3&commit=2&limit=50 | Pending commit queue jobs |
 | http://chromium-build-logs.appspot.com/      | Search for historical test failures by test name |
 | http://chromium-build-logs.appspot.com/list  | Filterable list of most recent build logs |
 
 ## For Sheriffs
 
+|:---------------------------------------------------------------------------------------------------------|:-------------------------------------------------------------------------|
 | http://build.chromium.org/p/chromium.chromiumos/waterfall?show_events=true&reload=120&failures_only=true | List of failing bots for a waterfall (chromium.chromiumos as an example) |
-|:---------------------------------------------------------------------------------------------------------|:-------------------------------------------------------------------------|
 | http://build.chromium.org/p/chromium.linux/waterfall?show_events=true&reload=120&builder=Linux%20Builder%20x64&builder=Linux%20Builder%20(dbg) | Monitor one or multiple bots (Linux Builder x64 and Linux Builder (dbg) on chromium.linux as an example) |
 | http://build.chromium.org/p/chromium.win/waterfall/help                                                  | Customize the waterfall view for a waterfall (using chromium.win as an example) |
 | http://chromium-sheriffing.appspot.com                                                                   | Alternate waterfall view that helps with test failure triage             |
 | http://test-results.appspot.com/dashboards/flakiness_dashboard.html                                      | Lists historical test results for the bots                               |
 
 ## Release Information
 
+|:--------------------------------------|:---------------------------------------------------|
 | https://omahaproxy.appspot.com/viewer | Current release versions of Chrome on all channels |
-|:--------------------------------------|:---------------------------------------------------|
 | https://omahaproxy.appspot.com/       | Looks up the revision of a build/release version   |
 
 ## Source Information
 
+|:------------------------|:------------|
 | http://cs.chromium.org/ | Code Search |
-|:------------------------|:------------|
 | http://cs.chromium.org/SEARCH_TERM | Code Search for a specific SEARCH\_TERM |
 | http://src.chromium.org/viewvc/chrome/ | ViewVC History Viewer |
 | http://git.chromium.org/gitweb/?p=chromium.git;a=summary | Gitweb History Viewer |
 | https://chromium.googlesource.com/chromium/src/+log/b6cfa6a..9a2e0a8?pretty=fuller | Git changes in revision range (also works for build numbers) |
 | http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog.html?url=/trunk/src&mode=html&range=SUCCESS_REV:FAILURE_REV | SVN changes in revision range |
 | http://build.chromium.org/f/chromium/perf/dashboard/ui/changelog_blink.html?url=/trunk&mode=html&range=SUCCESS_REV:FAILURE_REV | Blink changes in revision range |
 
 ## Communication
 
+|:------------------------------------------------------------------|:-------------------------|
 | http://groups.google.com/a/chromium.org/group/chromium-dev/topics | Chromium Developers List |
-|:------------------------------------------------------------------|:-------------------------|
 | http://groups.google.com/a/chromium.org/group/chromium-discuss/topics | Chromium Users List      |
-| http://code.google.com/p/chromium/source/list                     | Wiki History (SVN-based) |
-| http://code.google.com/p/chromium/wiki/UserHandleMapping          | Chromium User Mapping    |