Broken internal links

[msamsel]

New link validator exposed broken links (in hash fragment) in guides. We should correct them
Presented links are given in such order
Error: Invalid internal links in /test-page.html:
* 'href attribute' - text value
E.g. for link: <a href='invalid.url'>Nice text</a> placed on page test-page.html error will look like:
Error: Invalid internal links in /test-page.html:
* 'invalid.url' - Nice text

Full list of broken links:

Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_acf.html:
  * 'dev_disallowed_content.html#how-to-allow-everything-except&' - Disallowed Content
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_contributing_code.html:
  * 'dev_contributing.html#proposing-incomplete-patches' - incomplete pull request
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_drop_paste.html:
  * '#filtering' - Advanced Content Filter and paste filter
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_example_setups.html:
  * 'dev_plugins.html#through-ckbuilder' - Installing Plugins – Online Builder Installation
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_file_upload.html:
  * 'dev_file_browse_upload.html#using-ckfinder' - CKFinder Integration
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_howtos_dialog_windows.html:
  * '#how-do-i-learn-the-names-of-ckeditor-dialog-window-fields%3F' - Developer Tools
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_howtos_scayt.html:
  * 'dev_spellcheck.html#spell-check-as-you-type-%28scayt%29' - Spell Check As You Type (SCAYT)
  * 'dev_spellcheck.html#spell-check-as-you-type-%28scayt%29' - Spell Check As You Type (SCAYT)
  * 'dev_spellcheck.html#spell-check-as-you-type-%28scayt%29' - SCAYT
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_howtos_styles.html:
  * '#how-do-i-customize-the-styles-drop-down-list%3F' - described here
  * '#how-do-i-customize-the-styles-drop-down-list%3F' - How Do I Customize the Styles Drop-Down List?
  * '#how-do-i-customize-the-styles-drop-down-list%3F' - custom style definitions
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_patching.html:
  * 'dev_build.html#about-ckbuilder-%28command-line%29' - CKBuilder
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_sourcearea.html:
  * 'dev_toolbar.html#item-by-item-configuration' - “item by item” toolbar configuration
Error: Invalid internal links in /ckeditor4/4.11.1/guide/dev_toolbar.html:
  * '#toolbar-groups-configuration' - toolbar groups
  * '#item-by-item-configuration' - item by item
Error: Invalid internal links in /ckeditor4/4.11.1/guide/plugin_sdk_sample_1.html:
  * 'dev_toolbar.html#toolbar-groups-configuration' - toolbar group
Error: Invalid internal links in /ckeditor4/4.11.1/guide/plugin_sdk_sample.html:
  * 'dev_toolbar.html#toolbar-groups-configuration' - toolbar group