lexer: temporarily revert #\ patch; keep CR in comment bug fix

This commit temporarily reverts the commit that allows #\ "tcl-style"
comments everywhere and documents them, for the 1.7.1 patch release
cca1f7d18f.

\r is removed from the list of characters not allowed in a comment to
preserve that bugfix.

docs/content/manual/manual.yml

@@ -229,7 +229,7 @@ sections:
       * `-f filename` / `--from-file filename`:
 
         Read filter from the file rather than from a command line, like
-        awk's -f option.
+        awk's -f option. You can also use '#' to make comments.
 
       * `-L directory`:
 
@@ -3537,68 +3537,6 @@ sections:
               (.posts[] | select(.author == "stedolan") | .comments) |=
                   . + ["terrible."]
 
-  - title: Comments
-
-    body: |
-
-      You can write comments in your jq filters using `#`.
-
-      A `#` character (not part of a string) starts a comment.
-      All characters from `#` to the end of the line are ignored.
-
-      If the end of the line is preceded by an odd number of backslash
-      characters, the following line is also considered part of the
-      comment and is ignored.
-
-      For example, the following code outputs `[1,3,4,7]`
-
-          [
-            1,
-            # foo \
-            2,
-            # bar \\
-            3,
-            4, # baz \\\
-            5, \
-            6,
-            7
-            # comment \
-              comment \
-              comment
-          ]
-
-      Backslash continuing the comment on the next line can be useful
-      when writing the "shebang" for a jq script:
-
-          #!/bin/sh --
-          # sum - Output the sum of the given arguments (or stdin)
-          # usage: sum [numbers...]
-          # \
-          exec jq --args -MRnf "$0" -- "$@"
-
-          $ARGS.positional |
-          reduce (
-            if . == []
-              then inputs
-              else .[]
-            end |
-            . as $dot |
-            try tonumber catch false |
-            if not or isnan then
-              @json "sum: Invalid number \($dot).\n" | halt_error(1)
-            end
-          ) as $n (0; . + $n)
-
-      The `exec` line is considered a comment by jq, so it is ignored.
-      But it is not ignored by `sh`, since in `sh` a backslash at the
-      end of the line does not continue the comment.
-      With this trick, when the script is invoked as `sum 1 2`,
-      `/bin/sh -- /path/to/sum 1 2` will be run, and `sh` will then
-      run `exec jq --args -MRnf /path/to/sum -- 1 2` replacing itself
-      with a `jq` interpreter invoked with the specified options (`-M`,
-      `-R`, `-n`, `--args`), that evaluates the current file (`$0`),
-      with the arguments (`$@`) that were passed to `sh`.
-
   - title: Modules
     body: |