Small page/manual link fixes

[TymonKilich]

Hi, I've decided to try to do something useful as I was going through manual 😃

I fixed the links in the readme and at the index page of the manual (they didn't work). I also changed links from juliasymbolics.github.io/SymbolicUtils.jl to https://symbolicutils.juliasymbolics.org. Not sure whether it's the right way. I see the pages are in PkgPage.jl and it said to edit index.md directly.

I think it will be easier for first time contributors (such as me) if it was written what are the docs/pages built in. It says "Website built with Franklin.jl." at the bottom of the page, but I've found that PkgPage.jl is used only after looking at CI and gh-pages branch. So I added PkgPage.jl with link to "Website built with..." part in the footer.

[codecov-io]

Codecov Report

Merging #221 (9a3cb08) into master (b8945de) will decrease coverage by 0.10%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##           master     #221      +/-   ##
==========================================
- Coverage   86.10%   86.00%   -0.11%     
==========================================
  Files          12       12              
  Lines         993      993              
==========================================
- Hits          855      854       -1     
- Misses        138      139       +1     

Impacted Files	Coverage Δ
src/matchers.jl	94.23% <0.00%> (-1.93%)	⬇️

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[TymonKilich]

WIP: I've found some more breaks within the pages/manual due to associativity-commutativity (AC) rules being default now:

Please treat this PR as WIP.

• The first example in Rule based rewriting section doesn't work since sin(1 + z) + sin(1 + z) = 2sin(1 + z) automatically before application of the rule;
• Examples from predicates for matching don't work;
• Examples from associative-commutative rules don't work;
• Composing rewriters work but need some update due to automatic AC rules;
• Add some text about default AC rules to manual and possibly how to turn it off/overwrite it/apply custom rule first;

[shashi]

Thanks, these are awesome fixes!

Those broken examples are a bit of a good problem :-p the simplifications happen automatically. But we should fix it! It's my bad for not keeping an eye on them.

[TymonKilich]

I can try to fix the examples and come up with the new (hopefully adequate) ones if that's okay with you. :)

If yes should this be a part of this PR or should I create a new one and limit this one to just fixes of the links?

[shashi]

Of course, thank you!! In this PR is fine!

[MasonProtter]

Maybe we should just merge this one in the meantime and open a new PR for the example so these problems get fixed ASAP.

Are the test failures real? I don't see how this could break DataDrivenDiffEq or ModelingToolkit. I'll just re-run the tests.

[TymonKilich]

Sure, by all means merge as it is. Fixing manual takes a bit more time than I thought and I'll do it in separate PR.

I have no idea why the test fail. I didn't touch anything related to tests.

[TymonKilich]

Maybe we should just merge this one in the meantime and open a new PR for the example so these problems get fixed ASAP.

I've almost fixed listed problems. I nearly finished Getting Started and Term Rewriting sections. Only two things left.
Can't really come up with good example for @acrule since now it simplifies by default and I'd like to have some nicer example for Composing rewriters.

I'll open a PR tomorrow (actually later today where I live). Haven't looked into Interfacing, Code generation and API Reference sections yet but they may be left for further PR if you prefer to fix examples ASAP.

[ChrisRackauckas]

Those downstream issues were some versioning things we fixed over the last day.